pdfjs-dist/src/shared/compatibility.js

/* Copyright 2017 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* eslint-disable no-extend-native */
/* globals VBArray, PDFJS, global */

'use strict';

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define('pdfjs/shared/compatibility', ['exports'], factory);
  } else if (typeof exports !== 'undefined') {
    factory(exports);
  } else {
    factory((root.pdfjsSharedCompatibility = {}));
  }
}(this, function (exports) {

// Skip compatibility checks for the extensions and if we already run
// this module.
if ((typeof PDFJSDev === 'undefined' ||
     !PDFJSDev.test('FIREFOX || MOZCENTRAL || CHROME')) &&
    (typeof PDFJS === 'undefined' || !PDFJS.compatibilityChecked)) {

var globalScope = (typeof window !== 'undefined') ? window :
                  (typeof global !== 'undefined') ? global :
                  (typeof self !== 'undefined') ? self : this;

var userAgent = (typeof navigator !== 'undefined' && navigator.userAgent) || '';
var isAndroid = /Android/.test(userAgent);
var isAndroidPre3 = /Android\s[0-2][^\d]/.test(userAgent);
var isAndroidPre5 = /Android\s[0-4][^\d]/.test(userAgent);
var isChrome = userAgent.indexOf('Chrom') >= 0;
var isChromeWithRangeBug = /Chrome\/(39|40)\./.test(userAgent);
var isIOSChrome = userAgent.indexOf('CriOS') >= 0;
var isIE = userAgent.indexOf('Trident') >= 0;
var isIOS = /\b(iPad|iPhone|iPod)(?=;)/.test(userAgent);
var isOpera = userAgent.indexOf('Opera') >= 0;
var isSafari = /Safari\//.test(userAgent) &&
               !/(Chrome\/|Android\s)/.test(userAgent);

var hasDOM = typeof window === 'object' && typeof document === 'object';

// Initializing PDFJS global object here, it case if we need to change/disable
// some PDF.js features, e.g. range requests
if (typeof PDFJS === 'undefined') {
  globalScope.PDFJS = {};
}

PDFJS.compatibilityChecked = true;

// Checking if the typed arrays are supported
// Support: iOS<6.0 (subarray), IE<10, Android<4.0
(function checkTypedArrayCompatibility() {
  if (typeof Uint8Array !== 'undefined') {
    // Support: iOS<6.0
    if (typeof Uint8Array.prototype.subarray === 'undefined') {
      Uint8Array.prototype.subarray = function subarray(start, end) {
        return new Uint8Array(this.slice(start, end));
      };
      Float32Array.prototype.subarray = function subarray(start, end) {
        return new Float32Array(this.slice(start, end));
      };
    }

    // Support: Android<4.1
    if (typeof Float64Array === 'undefined') {
      globalScope.Float64Array = Float32Array;
    }
    return;
  }

  function subarray(start, end) {
    return new TypedArray(this.slice(start, end));
  }

  function setArrayOffset(array, offset) {
    if (arguments.length < 2) {
      offset = 0;
    }
    for (var i = 0, n = array.length; i < n; ++i, ++offset) {
      this[offset] = array[i] & 0xFF;
    }
  }

  function Uint32ArrayView(buffer, length) {
    this.buffer = buffer;
    this.byteLength = buffer.length;
    this.length = length;
    ensureUint32ArrayViewProps(this.length);
  }
  Uint32ArrayView.prototype = Object.create(null);

  var uint32ArrayViewSetters = 0;
  function createUint32ArrayProp(index) {
    return {
      get() {
        var buffer = this.buffer, offset = index << 2;
        return (buffer[offset] | (buffer[offset + 1] << 8) |
          (buffer[offset + 2] << 16) | (buffer[offset + 3] << 24)) >>> 0;
      },
      set(value) {
        var buffer = this.buffer, offset = index << 2;
        buffer[offset] = value & 255;
        buffer[offset + 1] = (value >> 8) & 255;
        buffer[offset + 2] = (value >> 16) & 255;
        buffer[offset + 3] = (value >>> 24) & 255;
      }
    };
  }

  function ensureUint32ArrayViewProps(length) {
    while (uint32ArrayViewSetters < length) {
      Object.defineProperty(Uint32ArrayView.prototype,
        uint32ArrayViewSetters,
        createUint32ArrayProp(uint32ArrayViewSetters));
      uint32ArrayViewSetters++;
    }
  }

  function TypedArray(arg1) {
    var result, i, n;
    if (typeof arg1 === 'number') {
      result = [];
      for (i = 0; i < arg1; ++i) {
        result[i] = 0;
      }
    } else if ('slice' in arg1) {
      result = arg1.slice(0);
    } else {
      result = [];
      for (i = 0, n = arg1.length; i < n; ++i) {
        result[i] = arg1[i];
      }
    }

    result.subarray = subarray;
    result.buffer = result;
    result.byteLength = result.length;
    result.set = setArrayOffset;

    if (typeof arg1 === 'object' && arg1.buffer) {
      result.buffer = arg1.buffer;
    }
    return result;
  }

  globalScope.Uint8Array = TypedArray;
  globalScope.Int8Array = TypedArray;

  // we don't need support for set, byteLength for 32-bit array
  // so we can use the TypedArray as well
  globalScope.Int32Array = TypedArray;
  globalScope.Uint16Array = TypedArray;
  globalScope.Float32Array = TypedArray;
  globalScope.Float64Array = TypedArray;

  globalScope.Uint32Array = function () {
    if (arguments.length === 3) {
      // Building view for buffer, offset, and length
      if (arguments[1] !== 0) {
        throw new Error('offset !== 0 is not supported');
      }
      return new Uint32ArrayView(arguments[0], arguments[2]);
    }
    return TypedArray.apply(this, arguments);
  };
})();

// window.CanvasPixelArray.buffer/.byteLength
// Support: IE9
(function canvasPixelArrayBuffer() {
  if (!hasDOM || !window.CanvasPixelArray) {
    return;
  }
  var cpaProto = window.CanvasPixelArray.prototype;
  if ('buffer' in cpaProto) {
    return;
  }
  // Trying to fake CanvasPixelArray as Uint8ClampedArray.
  Object.defineProperty(cpaProto, 'buffer', {
    get() {
      return this;
    },
    enumerable: false,
    configurable: true
  });
  Object.defineProperty(cpaProto, 'byteLength', {
    get() {
      return this.length;
    },
    enumerable: false,
    configurable: true
  });
})();

// URL = URL || webkitURL
// Support: Safari<7, Android 4.2+
(function normalizeURLObject() {
  if (!globalScope.URL) {
    globalScope.URL = globalScope.webkitURL;
  }
})();

// Object.defineProperty()?
// Support: Android<4.0, Safari<5.1
(function checkObjectDefinePropertyCompatibility() {
  if (typeof Object.defineProperty !== 'undefined') {
    var definePropertyPossible = true;
    try {
      if (hasDOM) {
        // some browsers (e.g. safari) cannot use defineProperty() on DOM
        // objects and thus the native version is not sufficient
        Object.defineProperty(new Image(), 'id', { value: 'test' });
      }
      // ... another test for android gb browser for non-DOM objects
      var Test = function Test() {};
      Test.prototype = { get id() { } };
      Object.defineProperty(new Test(), 'id',
        { value: '', configurable: true, enumerable: true, writable: false });
    } catch (e) {
      definePropertyPossible = false;
    }
    if (definePropertyPossible) {
      return;
    }
  }

  Object.defineProperty = function objectDefineProperty(obj, name, def) {
    delete obj[name];
    if ('get' in def) {
      obj.__defineGetter__(name, def['get']);
    }
    if ('set' in def) {
      obj.__defineSetter__(name, def['set']);
    }
    if ('value' in def) {
      obj.__defineSetter__(name, function objectDefinePropertySetter(value) {
        this.__defineGetter__(name, function objectDefinePropertyGetter() {
          return value;
        });
        return value;
      });
      obj[name] = def.value;
    }
  };
})();


// No XMLHttpRequest#response?
// Support: IE<11, Android <4.0
(function checkXMLHttpRequestResponseCompatibility() {
  if (typeof XMLHttpRequest === 'undefined') {
    return;
  }
  var xhrPrototype = XMLHttpRequest.prototype;
  var xhr = new XMLHttpRequest();
  if (!('overrideMimeType' in xhr)) {
    // IE10 might have response, but not overrideMimeType
    // Support: IE10
    Object.defineProperty(xhrPrototype, 'overrideMimeType', {
      value: function xmlHttpRequestOverrideMimeType(mimeType) {}
    });
  }
  if ('responseType' in xhr) {
    return;
  }

  Object.defineProperty(xhrPrototype, 'responseType', {
    get: function xmlHttpRequestGetResponseType() {
      return this._responseType || 'text';
    },
    set: function xmlHttpRequestSetResponseType(value) {
      if (value === 'text' || value === 'arraybuffer') {
        this._responseType = value;
        if (value === 'arraybuffer' &&
            typeof this.overrideMimeType === 'function') {
          this.overrideMimeType('text/plain; charset=x-user-defined');
        }
      }
    }
  });

  // Support: IE9
  if (typeof VBArray !== 'undefined') {
    Object.defineProperty(xhrPrototype, 'response', {
      get: function xmlHttpRequestResponseGet() {
        if (this.responseType === 'arraybuffer') {
          return new Uint8Array(new VBArray(this.responseBody).toArray());
        }
        return this.responseText;
      }
    });
    return;
  }

  Object.defineProperty(xhrPrototype, 'response', {
    get: function xmlHttpRequestResponseGet() {
      if (this.responseType !== 'arraybuffer') {
        return this.responseText;
      }
      var text = this.responseText;
      var i, n = text.length;
      var result = new Uint8Array(n);
      for (i = 0; i < n; ++i) {
        result[i] = text.charCodeAt(i) & 0xFF;
      }
      return result.buffer;
    }
  });
})();

// window.btoa (base64 encode function) ?
// Support: IE<10
(function checkWindowBtoaCompatibility() {
  if ('btoa' in globalScope) {
    return;
  }

  var digits =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

  globalScope.btoa = function (chars) {
    var buffer = '';
    var i, n;
    for (i = 0, n = chars.length; i < n; i += 3) {
      var b1 = chars.charCodeAt(i) & 0xFF;
      var b2 = chars.charCodeAt(i + 1) & 0xFF;
      var b3 = chars.charCodeAt(i + 2) & 0xFF;
      var d1 = b1 >> 2, d2 = ((b1 & 3) << 4) | (b2 >> 4);
      var d3 = i + 1 < n ? ((b2 & 0xF) << 2) | (b3 >> 6) : 64;
      var d4 = i + 2 < n ? (b3 & 0x3F) : 64;
      buffer += (digits.charAt(d1) + digits.charAt(d2) +
                 digits.charAt(d3) + digits.charAt(d4));
    }
    return buffer;
  };
})();

// window.atob (base64 encode function)?
// Support: IE<10
(function checkWindowAtobCompatibility() {
  if ('atob' in globalScope) {
    return;
  }

  // https://github.com/davidchambers/Base64.js
  var digits =
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
  globalScope.atob = function (input) {
    input = input.replace(/=+$/, '');
    if (input.length % 4 === 1) {
      throw new Error('bad atob input');
    }
    for (
      // initialize result and counters
      var bc = 0, bs, buffer, idx = 0, output = '';
      // get next character
      (buffer = input.charAt(idx++));
      // character found in table?
      // initialize bit storage and add its ascii value
      ~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer,
        // and if not first of each 4 characters,
        // convert the first 8 bits to one ascii character
        bc++ % 4) ? output += String.fromCharCode(255 & bs >> (-2 * bc & 6)) : 0
    ) {
      // try to find character in table (0-63, not found => -1)
      buffer = digits.indexOf(buffer);
    }
    return output;
  };
})();

// Function.prototype.bind?
// Support: Android<4.0, iOS<6.0
(function checkFunctionPrototypeBindCompatibility() {
  if (typeof Function.prototype.bind !== 'undefined') {
    return;
  }

  Function.prototype.bind = function functionPrototypeBind(obj) {
    var fn = this, headArgs = Array.prototype.slice.call(arguments, 1);
    var bound = function functionPrototypeBindBound() {
      var args = headArgs.concat(Array.prototype.slice.call(arguments));
      return fn.apply(obj, args);
    };
    return bound;
  };
})();

// HTMLElement dataset property
// Support: IE<11, Safari<5.1, Android<4.0
(function checkDatasetProperty() {
  if (!hasDOM) {
    return;
  }
  var div = document.createElement('div');
  if ('dataset' in div) {
    return; // dataset property exists
  }

  Object.defineProperty(HTMLElement.prototype, 'dataset', {
    get() {
      if (this._dataset) {
        return this._dataset;
      }

      var dataset = {};
      for (var j = 0, jj = this.attributes.length; j < jj; j++) {
        var attribute = this.attributes[j];
        if (attribute.name.substring(0, 5) !== 'data-') {
          continue;
        }
        var key = attribute.name.substring(5).replace(/\-([a-z])/g,
          function(all, ch) {
            return ch.toUpperCase();
          });
        dataset[key] = attribute.value;
      }

      Object.defineProperty(this, '_dataset', {
        value: dataset,
        writable: false,
        enumerable: false
      });
      return dataset;
    },
    enumerable: true
  });
})();

// HTMLElement classList property
// Support: IE<10, Android<4.0, iOS<5.0
(function checkClassListProperty() {
  function changeList(element, itemName, add, remove) {
    var s = element.className || '';
    var list = s.split(/\s+/g);
    if (list[0] === '') {
      list.shift();
    }
    var index = list.indexOf(itemName);
    if (index < 0 && add) {
      list.push(itemName);
    }
    if (index >= 0 && remove) {
      list.splice(index, 1);
    }
    element.className = list.join(' ');
    return (index >= 0);
  }

  if (!hasDOM) {
    return;
  }

  var div = document.createElement('div');
  if ('classList' in div) {
    return; // classList property exists
  }

  var classListPrototype = {
    add(name) {
      changeList(this.element, name, true, false);
    },
    contains(name) {
      return changeList(this.element, name, false, false);
    },
    remove(name) {
      changeList(this.element, name, false, true);
    },
    toggle(name) {
      changeList(this.element, name, true, true);
    }
  };

  Object.defineProperty(HTMLElement.prototype, 'classList', {
    get() {
      if (this._classList) {
        return this._classList;
      }

      var classList = Object.create(classListPrototype, {
        element: {
          value: this,
          writable: false,
          enumerable: true
        }
      });
      Object.defineProperty(this, '_classList', {
        value: classList,
        writable: false,
        enumerable: false
      });
      return classList;
    },
    enumerable: true
  });
})();

// Checking if worker has console support. Forwarding all messages to the main
// thread if console object is absent.
(function checkWorkerConsoleCompatibility() {
  if (typeof importScripts === 'undefined' || 'console' in globalScope) {
    return;
  }

  var consoleTimer = {};

  var workerConsole = {
    log: function log() {
      var args = Array.prototype.slice.call(arguments);
      globalScope.postMessage({
        targetName: 'main',
        action: 'console_log',
        data: args
      });
    },

    error: function error() {
      var args = Array.prototype.slice.call(arguments);
      globalScope.postMessage({
        targetName: 'main',
        action: 'console_error',
        data: args
      });
    },

    time: function time(name) {
      consoleTimer[name] = Date.now();
    },

    timeEnd: function timeEnd(name) {
      var time = consoleTimer[name];
      if (!time) {
        throw new Error('Unknown timer name ' + name);
      }
      this.log('Timer:', name, Date.now() - time);
    }
  };

  globalScope.console = workerConsole;
})();

// Check console compatibility
// In older IE versions the console object is not available
// unless console is open.
// Support: IE<10
(function checkConsoleCompatibility() {
  if (!hasDOM) {
    return;
  }
  if (!('console' in window)) {
    window.console = {
      log() {},
      error() {},
      warn() {}
    };
    return;
  }
  if (!('bind' in console.log)) {
    // native functions in IE9 might not have bind
    console.log = (function(fn) {
      return function(msg) {
        return fn(msg);
      };
    })(console.log);
    console.error = (function(fn) {
      return function(msg) {
        return fn(msg);
      };
    })(console.error);
    console.warn = (function(fn) {
      return function(msg) {
        return fn(msg);
      };
    })(console.warn);
    return;
  }
})();

// Check onclick compatibility in Opera
// Support: Opera<15
(function checkOnClickCompatibility() {
  // workaround for reported Opera bug DSK-354448:
  // onclick fires on disabled buttons with opaque content
  function ignoreIfTargetDisabled(event) {
    if (isDisabled(event.target)) {
      event.stopPropagation();
    }
  }
  function isDisabled(node) {
    return node.disabled || (node.parentNode && isDisabled(node.parentNode));
  }
  if (isOpera) {
    // use browser detection since we cannot feature-check this bug
    document.addEventListener('click', ignoreIfTargetDisabled, true);
  }
})();

// Checks if possible to use URL.createObjectURL()
// Support: IE, Chrome on iOS
(function checkOnBlobSupport() {
  // sometimes IE and Chrome on iOS loosing the data created with
  // createObjectURL(), see #3977 and #8081
  if (isIE || isIOSChrome) {
    PDFJS.disableCreateObjectURL = true;
  }
})();

// Checks if navigator.language is supported
(function checkNavigatorLanguage() {
  if (typeof navigator === 'undefined') {
    return;
  }
  if ('language' in navigator) {
    return;
  }
  PDFJS.locale = navigator.userLanguage || 'en-US';
})();

// Support: Safari 6.0+, Android<3.0, Chrome 39/40, iOS
(function checkRangeRequests() {
  // Safari has issues with cached range requests see:
  // https://github.com/mozilla/pdf.js/issues/3260
  // Last tested with version 6.0.4.

  // Older versions of Android (pre 3.0) has issues with range requests, see:
  // https://github.com/mozilla/pdf.js/issues/3381.
  // Make sure that we only match webkit-based Android browsers,
  // since Firefox/Fennec works as expected.

  // Range requests are broken in Chrome 39 and 40, https://crbug.com/442318
  if (isSafari || isAndroidPre3 || isChromeWithRangeBug || isIOS) {
    PDFJS.disableRange = true;
    PDFJS.disableStream = true;
  }
})();

// Check if the browser supports manipulation of the history.
// Support: IE<10, Android<4.2
(function checkHistoryManipulation() {
  if (!hasDOM) {
    return;
  }
  // Android 2.x has so buggy pushState support that it was removed in
  // Android 3.0 and restored as late as in Android 4.2.
  // Support: Android 2.x
  if (!history.pushState || isAndroidPre3) {
    PDFJS.disableHistory = true;
  }
})();

// Support: IE<11, Chrome<21, Android<4.4, Safari<6
(function checkSetPresenceInImageData() {
  if (!hasDOM) {
    return;
  }
  // IE < 11 will use window.CanvasPixelArray which lacks set function.
  if (window.CanvasPixelArray) {
    if (typeof window.CanvasPixelArray.prototype.set !== 'function') {
      window.CanvasPixelArray.prototype.set = function(arr) {
        for (var i = 0, ii = this.length; i < ii; i++) {
          this[i] = arr[i];
        }
      };
    }
  } else {
    // Old Chrome and Android use an inaccessible CanvasPixelArray prototype.
    // Because we cannot feature detect it, we rely on user agent parsing.
    var polyfill = false, versionMatch;
    if (isChrome) {
      versionMatch = userAgent.match(/Chrom(e|ium)\/([0-9]+)\./);
      // Chrome < 21 lacks the set function.
      polyfill = versionMatch && parseInt(versionMatch[2]) < 21;
    } else if (isAndroid) {
      // Android < 4.4 lacks the set function.
      // Android >= 4.4 will contain Chrome in the user agent,
      // thus pass the Chrome check above and not reach this block.
      polyfill = isAndroidPre5;
    } else if (isSafari) {
      versionMatch = userAgent.
        match(/Version\/([0-9]+)\.([0-9]+)\.([0-9]+) Safari\//);
      // Safari < 6 lacks the set function.
      polyfill = versionMatch && parseInt(versionMatch[1]) < 6;
    }

    if (polyfill) {
      var contextPrototype = window.CanvasRenderingContext2D.prototype;
      var createImageData = contextPrototype.createImageData;
      contextPrototype.createImageData = function(w, h) {
        var imageData = createImageData.call(this, w, h);
        imageData.data.set = function(arr) {
          for (var i = 0, ii = this.length; i < ii; i++) {
            this[i] = arr[i];
          }
        };
        return imageData;
      };
      // this closure will be kept referenced, so clear its vars
      contextPrototype = null;
    }
  }
})();

// Support: IE<10, Android<4.0, iOS
(function checkRequestAnimationFrame() {
  function installFakeAnimationFrameFunctions() {
    window.requestAnimationFrame = function (callback) {
      return window.setTimeout(callback, 20);
    };
    window.cancelAnimationFrame = function (timeoutID) {
      window.clearTimeout(timeoutID);
    };
  }

  if (!hasDOM) {
    return;
  }
  if (isIOS) {
    // requestAnimationFrame on iOS is broken, replacing with fake one.
    installFakeAnimationFrameFunctions();
    return;
  }
  if ('requestAnimationFrame' in window) {
    return;
  }
  window.requestAnimationFrame = window.mozRequestAnimationFrame ||
                                 window.webkitRequestAnimationFrame;
  if (window.requestAnimationFrame) {
    return;
  }
  installFakeAnimationFrameFunctions();
})();

// Support: Android, iOS
(function checkCanvasSizeLimitation() {
  if (isIOS || isAndroid) {
    // 5MP
    PDFJS.maxCanvasPixels = 5242880;
  }
})();

// Disable fullscreen support for certain problematic configurations.
// Support: IE11+ (when embedded).
(function checkFullscreenSupport() {
  if (!hasDOM) {
    return;
  }
  if (isIE && window.parent !== window) {
    PDFJS.disableFullscreen = true;
  }
})();

// Provides document.currentScript support
// Support: IE, Chrome<29.
(function checkCurrentScript() {
  if (!hasDOM) {
    return;
  }
  if ('currentScript' in document) {
    return;
  }
  Object.defineProperty(document, 'currentScript', {
    get() {
      var scripts = document.getElementsByTagName('script');
      return scripts[scripts.length - 1];
    },
    enumerable: true,
    configurable: true
  });
})();

// Provides `input.type = 'type'` runtime failure protection.
// Support: IE9,10.
(function checkInputTypeNumberAssign() {
  if (!hasDOM) {
    return;
  }
  var el = document.createElement('input');
  try {
    el.type = 'number';
  } catch (ex) {
    var inputProto = el.constructor.prototype;
    var typeProperty = Object.getOwnPropertyDescriptor(inputProto, 'type');
    Object.defineProperty(inputProto, 'type', {
      get() {
        return typeProperty.get.call(this);
      },
      set(value) {
        typeProperty.set.call(this, value === 'number' ? 'text' : value);
      },
      enumerable: true,
      configurable: true
    });
  }
})();

// Provides correct document.readyState value for legacy browsers.
// Support: IE9,10.
(function checkDocumentReadyState() {
  if (!hasDOM) {
    return;
  }
  if (!document.attachEvent) {
    return;
  }
  var documentProto = document.constructor.prototype;
  var readyStateProto = Object.getOwnPropertyDescriptor(documentProto,
                                                        'readyState');
  Object.defineProperty(documentProto, 'readyState', {
    get() {
      var value = readyStateProto.get.call(this);
      return value === 'interactive' ? 'loading' : value;
    },
    set(value) {
      readyStateProto.set.call(this, value);
    },
    enumerable: true,
    configurable: true
  });
})();

// Provides support for ChildNode.remove in legacy browsers.
// Support: IE.
(function checkChildNodeRemove() {
  if (!hasDOM) {
    return;
  }
  if (typeof Element.prototype.remove !== 'undefined') {
    return;
  }
  Element.prototype.remove = function () {
    if (this.parentNode) {
      this.parentNode.removeChild(this);
    }
  };
})();

/**
 * Polyfill for Promises:
 * The following promise implementation tries to generally implement the
 * Promise/A+ spec. Some notable differences from other promise libraries are:
 * - There currently isn't a separate deferred and promise object.
 * - Unhandled rejections eventually show an error if they aren't handled.
 *
 * Based off of the work in:
 * https://bugzilla.mozilla.org/show_bug.cgi?id=810490
 */
(function checkPromise() {
  if (globalScope.Promise) {
    // Promises existing in the DOM/Worker, checking presence of all/resolve
    if (typeof globalScope.Promise.all !== 'function') {
      globalScope.Promise.all = function (iterable) {
        var count = 0, results = [], resolve, reject;
        var promise = new globalScope.Promise(function (resolve_, reject_) {
          resolve = resolve_;
          reject = reject_;
        });
        iterable.forEach(function (p, i) {
          count++;
          p.then(function (result) {
            results[i] = result;
            count--;
            if (count === 0) {
              resolve(results);
            }
          }, reject);
        });
        if (count === 0) {
          resolve(results);
        }
        return promise;
      };
    }
    if (typeof globalScope.Promise.resolve !== 'function') {
      globalScope.Promise.resolve = function (value) {
        return new globalScope.Promise(function (resolve) {
          resolve(value);
        });
      };
    }
    if (typeof globalScope.Promise.reject !== 'function') {
      globalScope.Promise.reject = function (reason) {
        return new globalScope.Promise(function (resolve, reject) {
          reject(reason);
        });
      };
    }
    if (typeof globalScope.Promise.prototype.catch !== 'function') {
      globalScope.Promise.prototype.catch = function (onReject) {
        return globalScope.Promise.prototype.then(undefined, onReject);
      };
    }
    return;
  }

  var STATUS_PENDING = 0;
  var STATUS_RESOLVED = 1;
  var STATUS_REJECTED = 2;

  // In an attempt to avoid silent exceptions, unhandled rejections are
  // tracked and if they aren't handled in a certain amount of time an
  // error is logged.
  var REJECTION_TIMEOUT = 500;

  var HandlerManager = {
    handlers: [],
    running: false,
    unhandledRejections: [],
    pendingRejectionCheck: false,

    scheduleHandlers: function scheduleHandlers(promise) {
      if (promise._status === STATUS_PENDING) {
        return;
      }

      this.handlers = this.handlers.concat(promise._handlers);
      promise._handlers = [];

      if (this.running) {
        return;
      }
      this.running = true;

      setTimeout(this.runHandlers.bind(this), 0);
    },

    runHandlers: function runHandlers() {
      var RUN_TIMEOUT = 1; // ms
      var timeoutAt = Date.now() + RUN_TIMEOUT;
      while (this.handlers.length > 0) {
        var handler = this.handlers.shift();

        var nextStatus = handler.thisPromise._status;
        var nextValue = handler.thisPromise._value;

        try {
          if (nextStatus === STATUS_RESOLVED) {
            if (typeof handler.onResolve === 'function') {
              nextValue = handler.onResolve(nextValue);
            }
          } else if (typeof handler.onReject === 'function') {
              nextValue = handler.onReject(nextValue);
              nextStatus = STATUS_RESOLVED;

              if (handler.thisPromise._unhandledRejection) {
                this.removeUnhandeledRejection(handler.thisPromise);
              }
          }
        } catch (ex) {
          nextStatus = STATUS_REJECTED;
          nextValue = ex;
        }

        handler.nextPromise._updateStatus(nextStatus, nextValue);
        if (Date.now() >= timeoutAt) {
          break;
        }
      }

      if (this.handlers.length > 0) {
        setTimeout(this.runHandlers.bind(this), 0);
        return;
      }

      this.running = false;
    },

    addUnhandledRejection: function addUnhandledRejection(promise) {
      this.unhandledRejections.push({
        promise,
        time: Date.now()
      });
      this.scheduleRejectionCheck();
    },

    removeUnhandeledRejection: function removeUnhandeledRejection(promise) {
      promise._unhandledRejection = false;
      for (var i = 0; i < this.unhandledRejections.length; i++) {
        if (this.unhandledRejections[i].promise === promise) {
          this.unhandledRejections.splice(i);
          i--;
        }
      }
    },

    scheduleRejectionCheck: function scheduleRejectionCheck() {
      if (this.pendingRejectionCheck) {
        return;
      }
      this.pendingRejectionCheck = true;
      setTimeout(function rejectionCheck() {
        this.pendingRejectionCheck = false;
        var now = Date.now();
        for (var i = 0; i < this.unhandledRejections.length; i++) {
          if (now - this.unhandledRejections[i].time > REJECTION_TIMEOUT) {
            var unhandled = this.unhandledRejections[i].promise._value;
            var msg = 'Unhandled rejection: ' + unhandled;
            if (unhandled.stack) {
              msg += '\n' + unhandled.stack;
            }
            // Raising and catching the error, so debugger can break on it.
            try {
              throw new Error(msg);
            } catch (_) {
              console.warn(msg);
            }
            this.unhandledRejections.splice(i);
            i--;
          }
        }
        if (this.unhandledRejections.length) {
          this.scheduleRejectionCheck();
        }
      }.bind(this), REJECTION_TIMEOUT);
    }
  };

  var Promise = function Promise(resolver) {
    this._status = STATUS_PENDING;
    this._handlers = [];
    try {
      resolver.call(this, this._resolve.bind(this), this._reject.bind(this));
    } catch (e) {
      this._reject(e);
    }
  };

  /**
   * Builds a promise that is resolved when all the passed in promises are
   * resolved.
   * @param {array} promises array of data and/or promises to wait for.
   * @return {Promise} New dependent promise.
   */
  Promise.all = function Promise_all(promises) {
    var resolveAll, rejectAll;
    var deferred = new Promise(function (resolve, reject) {
      resolveAll = resolve;
      rejectAll = reject;
    });
    var unresolved = promises.length;
    var results = [];
    if (unresolved === 0) {
      resolveAll(results);
      return deferred;
    }
    function reject(reason) {
      if (deferred._status === STATUS_REJECTED) {
        return;
      }
      results = [];
      rejectAll(reason);
    }
    for (var i = 0, ii = promises.length; i < ii; ++i) {
      var promise = promises[i];
      var resolve = (function(i) {
        return function(value) {
          if (deferred._status === STATUS_REJECTED) {
            return;
          }
          results[i] = value;
          unresolved--;
          if (unresolved === 0) {
            resolveAll(results);
          }
        };
      })(i);
      if (Promise.isPromise(promise)) {
        promise.then(resolve, reject);
      } else {
        resolve(promise);
      }
    }
    return deferred;
  };

  /**
   * Checks if the value is likely a promise (has a 'then' function).
   * @return {boolean} true if value is thenable
   */
  Promise.isPromise = function Promise_isPromise(value) {
    return value && typeof value.then === 'function';
  };

  /**
   * Creates resolved promise
   * @param value resolve value
   * @returns {Promise}
   */
  Promise.resolve = function Promise_resolve(value) {
    return new Promise(function (resolve) {
      resolve(value);
    });
  };

  /**
   * Creates rejected promise
   * @param reason rejection value
   * @returns {Promise}
   */
  Promise.reject = function Promise_reject(reason) {
    return new Promise(function (resolve, reject) {
      reject(reason);
    });
  };

  Promise.prototype = {
    _status: null,
    _value: null,
    _handlers: null,
    _unhandledRejection: null,

    _updateStatus: function Promise__updateStatus(status, value) {
      if (this._status === STATUS_RESOLVED ||
          this._status === STATUS_REJECTED) {
        return;
      }

      if (status === STATUS_RESOLVED &&
          Promise.isPromise(value)) {
        value.then(this._updateStatus.bind(this, STATUS_RESOLVED),
                   this._updateStatus.bind(this, STATUS_REJECTED));
        return;
      }

      this._status = status;
      this._value = value;

      if (status === STATUS_REJECTED && this._handlers.length === 0) {
        this._unhandledRejection = true;
        HandlerManager.addUnhandledRejection(this);
      }

      HandlerManager.scheduleHandlers(this);
    },

    _resolve: function Promise_resolve(value) {
      this._updateStatus(STATUS_RESOLVED, value);
    },

    _reject: function Promise_reject(reason) {
      this._updateStatus(STATUS_REJECTED, reason);
    },

    then: function Promise_then(onResolve, onReject) {
      var nextPromise = new Promise(function (resolve, reject) {
        this.resolve = resolve;
        this.reject = reject;
      });
      this._handlers.push({
        thisPromise: this,
        onResolve,
        onReject,
        nextPromise,
      });
      HandlerManager.scheduleHandlers(this);
      return nextPromise;
    },

    catch: function Promise_catch(onReject) {
      return this.then(undefined, onReject);
    }
  };

  globalScope.Promise = Promise;
})();

(function checkWeakMap() {
  if (globalScope.WeakMap) {
    return;
  }

  var id = 0;
  function WeakMap() {
    this.id = '$weakmap' + (id++);
  }
  WeakMap.prototype = {
    has(obj) {
      return !!Object.getOwnPropertyDescriptor(obj, this.id);
    },
    get(obj, defaultValue) {
      return this.has(obj) ? obj[this.id] : defaultValue;
    },
    set(obj, value) {
      Object.defineProperty(obj, this.id, {
        value,
        enumerable: false,
        configurable: true
      });
    },
    delete(obj) {
      delete obj[this.id];
    }
  };

  globalScope.WeakMap = WeakMap;
})();

// Polyfill from https://github.com/Polymer/URL
/* Any copyright is dedicated to the Public Domain.
 * http://creativecommons.org/publicdomain/zero/1.0/ */
(function checkURLConstructor() {
  // feature detect for URL constructor
  var hasWorkingUrl = false;
  try {
    if (typeof URL === 'function' &&
        typeof URL.prototype === 'object' &&
        ('origin' in URL.prototype)) {
      var u = new URL('b', 'http://a');
      u.pathname = 'c%20d';
      hasWorkingUrl = u.href === 'http://a/c%20d';
    }
  } catch (e) { }

  if (hasWorkingUrl) {
    return;
  }

  var relative = Object.create(null);
  relative['ftp'] = 21;
  relative['file'] = 0;
  relative['gopher'] = 70;
  relative['http'] = 80;
  relative['https'] = 443;
  relative['ws'] = 80;
  relative['wss'] = 443;

  var relativePathDotMapping = Object.create(null);
  relativePathDotMapping['%2e'] = '.';
  relativePathDotMapping['.%2e'] = '..';
  relativePathDotMapping['%2e.'] = '..';
  relativePathDotMapping['%2e%2e'] = '..';

  function isRelativeScheme(scheme) {
    return relative[scheme] !== undefined;
  }

  function invalid() {
    clear.call(this);
    this._isInvalid = true;
  }

  function IDNAToASCII(h) {
    if (h === '') {
      invalid.call(this);
    }
    // XXX
    return h.toLowerCase();
  }

  function percentEscape(c) {
    var unicode = c.charCodeAt(0);
    if (unicode > 0x20 &&
       unicode < 0x7F &&
       // " # < > ? `
       [0x22, 0x23, 0x3C, 0x3E, 0x3F, 0x60].indexOf(unicode) === -1
      ) {
      return c;
    }
    return encodeURIComponent(c);
  }

  function percentEscapeQuery(c) {
    // XXX This actually needs to encode c using encoding and then
    // convert the bytes one-by-one.

    var unicode = c.charCodeAt(0);
    if (unicode > 0x20 &&
       unicode < 0x7F &&
       // " # < > ` (do not escape '?')
       [0x22, 0x23, 0x3C, 0x3E, 0x60].indexOf(unicode) === -1
      ) {
      return c;
    }
    return encodeURIComponent(c);
  }

  var EOF, ALPHA = /[a-zA-Z]/,
      ALPHANUMERIC = /[a-zA-Z0-9\+\-\.]/;

  function parse(input, stateOverride, base) {
    function err(message) {
      errors.push(message);
    }

    var state = stateOverride || 'scheme start',
        cursor = 0,
        buffer = '',
        seenAt = false,
        seenBracket = false,
        errors = [];

    loop: while ((input[cursor - 1] !== EOF || cursor === 0) &&
                 !this._isInvalid) {
      var c = input[cursor];
      switch (state) {
        case 'scheme start':
          if (c && ALPHA.test(c)) {
            buffer += c.toLowerCase(); // ASCII-safe
            state = 'scheme';
          } else if (!stateOverride) {
            buffer = '';
            state = 'no scheme';
            continue;
          } else {
            err('Invalid scheme.');
            break loop;
          }
          break;

        case 'scheme':
          if (c && ALPHANUMERIC.test(c)) {
            buffer += c.toLowerCase(); // ASCII-safe
          } else if (c === ':') {
            this._scheme = buffer;
            buffer = '';
            if (stateOverride) {
              break loop;
            }
            if (isRelativeScheme(this._scheme)) {
              this._isRelative = true;
            }
            if (this._scheme === 'file') {
              state = 'relative';
            } else if (this._isRelative && base &&
                       base._scheme === this._scheme) {
              state = 'relative or authority';
            } else if (this._isRelative) {
              state = 'authority first slash';
            } else {
              state = 'scheme data';
            }
          } else if (!stateOverride) {
            buffer = '';
            cursor = 0;
            state = 'no scheme';
            continue;
          } else if (c === EOF) {
            break loop;
          } else {
            err('Code point not allowed in scheme: ' + c);
            break loop;
          }
          break;

        case 'scheme data':
          if (c === '?') {
            this._query = '?';
            state = 'query';
          } else if (c === '#') {
            this._fragment = '#';
            state = 'fragment';
          } else {
            // XXX error handling
            if (c !== EOF && c !== '\t' && c !== '\n' && c !== '\r') {
              this._schemeData += percentEscape(c);
            }
          }
          break;

        case 'no scheme':
          if (!base || !(isRelativeScheme(base._scheme))) {
            err('Missing scheme.');
            invalid.call(this);
          } else {
            state = 'relative';
            continue;
          }
          break;

        case 'relative or authority':
          if (c === '/' && input[cursor + 1] === '/') {
            state = 'authority ignore slashes';
          } else {
            err('Expected /, got: ' + c);
            state = 'relative';
            continue;
          }
          break;

        case 'relative':
          this._isRelative = true;
          if (this._scheme !== 'file') {
            this._scheme = base._scheme;
          }
          if (c === EOF) {
            this._host = base._host;
            this._port = base._port;
            this._path = base._path.slice();
            this._query = base._query;
            this._username = base._username;
            this._password = base._password;
            break loop;
          } else if (c === '/' || c === '\\') {
            if (c === '\\') {
              err('\\ is an invalid code point.');
            }
            state = 'relative slash';
          } else if (c === '?') {
            this._host = base._host;
            this._port = base._port;
            this._path = base._path.slice();
            this._query = '?';
            this._username = base._username;
            this._password = base._password;
            state = 'query';
          } else if (c === '#') {
            this._host = base._host;
            this._port = base._port;
            this._path = base._path.slice();
            this._query = base._query;
            this._fragment = '#';
            this._username = base._username;
            this._password = base._password;
            state = 'fragment';
          } else {
            var nextC = input[cursor + 1];
            var nextNextC = input[cursor + 2];
            if (this._scheme !== 'file' || !ALPHA.test(c) ||
                (nextC !== ':' && nextC !== '|') ||
                (nextNextC !== EOF && nextNextC !== '/' && nextNextC !== '\\' &&
                 nextNextC !== '?' && nextNextC !== '#')) {
              this._host = base._host;
              this._port = base._port;
              this._username = base._username;
              this._password = base._password;
              this._path = base._path.slice();
              this._path.pop();
            }
            state = 'relative path';
            continue;
          }
          break;

        case 'relative slash':
          if (c === '/' || c === '\\') {
            if (c === '\\') {
              err('\\ is an invalid code point.');
            }
            if (this._scheme === 'file') {
              state = 'file host';
            } else {
              state = 'authority ignore slashes';
            }
          } else {
            if (this._scheme !== 'file') {
              this._host = base._host;
              this._port = base._port;
              this._username = base._username;
              this._password = base._password;
            }
            state = 'relative path';
            continue;
          }
          break;

        case 'authority first slash':
          if (c === '/') {
            state = 'authority second slash';
          } else {
            err('Expected \'/\', got: ' + c);
            state = 'authority ignore slashes';
            continue;
          }
          break;

        case 'authority second slash':
          state = 'authority ignore slashes';
          if (c !== '/') {
            err('Expected \'/\', got: ' + c);
            continue;
          }
          break;

        case 'authority ignore slashes':
          if (c !== '/' && c !== '\\') {
            state = 'authority';
            continue;
          } else {
            err('Expected authority, got: ' + c);
          }
          break;

        case 'authority':
          if (c === '@') {
            if (seenAt) {
              err('@ already seen.');
              buffer += '%40';
            }
            seenAt = true;
            for (var i = 0; i < buffer.length; i++) {
              var cp = buffer[i];
              if (cp === '\t' || cp === '\n' || cp === '\r') {
                err('Invalid whitespace in authority.');
                continue;
              }
              // XXX check URL code points
              if (cp === ':' && this._password === null) {
                this._password = '';
                continue;
              }
              var tempC = percentEscape(cp);
              if (this._password !== null) {
                this._password += tempC;
              } else {
                this._username += tempC;
              }
            }
            buffer = '';
          } else if (c === EOF || c === '/' || c === '\\' ||
                     c === '?' || c === '#') {
            cursor -= buffer.length;
            buffer = '';
            state = 'host';
            continue;
          } else {
            buffer += c;
          }
          break;

        case 'file host':
          if (c === EOF || c === '/' || c === '\\' || c === '?' || c === '#') {
            if (buffer.length === 2 && ALPHA.test(buffer[0]) &&
                (buffer[1] === ':' || buffer[1] === '|')) {
              state = 'relative path';
            } else if (buffer.length === 0) {
              state = 'relative path start';
            } else {
              this._host = IDNAToASCII.call(this, buffer);
              buffer = '';
              state = 'relative path start';
            }
            continue;
          } else if (c === '\t' || c === '\n' || c === '\r') {
            err('Invalid whitespace in file host.');
          } else {
            buffer += c;
          }
          break;

        case 'host':
        case 'hostname':
          if (c === ':' && !seenBracket) {
            // XXX host parsing
            this._host = IDNAToASCII.call(this, buffer);
            buffer = '';
            state = 'port';
            if (stateOverride === 'hostname') {
              break loop;
            }
          } else if (c === EOF || c === '/' ||
                     c === '\\' || c === '?' || c === '#') {
            this._host = IDNAToASCII.call(this, buffer);
            buffer = '';
            state = 'relative path start';
            if (stateOverride) {
              break loop;
            }
            continue;
          } else if (c !== '\t' && c !== '\n' && c !== '\r') {
            if (c === '[') {
              seenBracket = true;
            } else if (c === ']') {
              seenBracket = false;
            }
            buffer += c;
          } else {
            err('Invalid code point in host/hostname: ' + c);
          }
          break;

        case 'port':
          if (/[0-9]/.test(c)) {
            buffer += c;
          } else if (c === EOF || c === '/' || c === '\\' ||
                     c === '?' || c === '#' || stateOverride) {
            if (buffer !== '') {
              var temp = parseInt(buffer, 10);
              if (temp !== relative[this._scheme]) {
                this._port = temp + '';
              }
              buffer = '';
            }
            if (stateOverride) {
              break loop;
            }
            state = 'relative path start';
            continue;
          } else if (c === '\t' || c === '\n' || c === '\r') {
            err('Invalid code point in port: ' + c);
          } else {
            invalid.call(this);
          }
          break;

        case 'relative path start':
          if (c === '\\') {
            err('\'\\\' not allowed in path.');
          }
          state = 'relative path';
          if (c !== '/' && c !== '\\') {
            continue;
          }
          break;

        case 'relative path':
          if (c === EOF || c === '/' || c === '\\' ||
              (!stateOverride && (c === '?' || c === '#'))) {
            if (c === '\\') {
              err('\\ not allowed in relative path.');
            }
            var tmp;
            if ((tmp = relativePathDotMapping[buffer.toLowerCase()])) {
              buffer = tmp;
            }
            if (buffer === '..') {
              this._path.pop();
              if (c !== '/' && c !== '\\') {
                this._path.push('');
              }
            } else if (buffer === '.' && c !== '/' && c !== '\\') {
              this._path.push('');
            } else if (buffer !== '.') {
              if (this._scheme === 'file' && this._path.length === 0 &&
                  buffer.length === 2 && ALPHA.test(buffer[0]) &&
                  buffer[1] === '|') {
                buffer = buffer[0] + ':';
              }
              this._path.push(buffer);
            }
            buffer = '';
            if (c === '?') {
              this._query = '?';
              state = 'query';
            } else if (c === '#') {
              this._fragment = '#';
              state = 'fragment';
            }
          } else if (c !== '\t' && c !== '\n' && c !== '\r') {
            buffer += percentEscape(c);
          }
          break;

        case 'query':
          if (!stateOverride && c === '#') {
            this._fragment = '#';
            state = 'fragment';
          } else if (c !== EOF && c !== '\t' && c !== '\n' && c !== '\r') {
            this._query += percentEscapeQuery(c);
          }
          break;

        case 'fragment':
          if (c !== EOF && c !== '\t' && c !== '\n' && c !== '\r') {
            this._fragment += c;
          }
          break;
      }

      cursor++;
    }
  }

  function clear() {
    this._scheme = '';
    this._schemeData = '';
    this._username = '';
    this._password = null;
    this._host = '';
    this._port = '';
    this._path = [];
    this._query = '';
    this._fragment = '';
    this._isInvalid = false;
    this._isRelative = false;
  }

  // Does not process domain names or IP addresses.
  // Does not handle encoding for the query parameter.
  function JURL(url, base /* , encoding */) {
    if (base !== undefined && !(base instanceof JURL)) {
      base = new JURL(String(base));
    }

    this._url = url;
    clear.call(this);

    var input = url.replace(/^[ \t\r\n\f]+|[ \t\r\n\f]+$/g, '');
    // encoding = encoding || 'utf-8'

    parse.call(this, input, null, base);
  }

  JURL.prototype = {
    toString() {
      return this.href;
    },
    get href() {
      if (this._isInvalid) {
        return this._url;
      }
      var authority = '';
      if (this._username !== '' || this._password !== null) {
        authority = this._username +
          (this._password !== null ? ':' + this._password : '') + '@';
      }

      return this.protocol +
          (this._isRelative ? '//' + authority + this.host : '') +
          this.pathname + this._query + this._fragment;
    },
    set href(href) {
      clear.call(this);
      parse.call(this, href);
    },

    get protocol() {
      return this._scheme + ':';
    },
    set protocol(protocol) {
      if (this._isInvalid) {
        return;
      }
      parse.call(this, protocol + ':', 'scheme start');
    },

    get host() {
      return this._isInvalid ? '' : this._port ?
          this._host + ':' + this._port : this._host;
    },
    set host(host) {
      if (this._isInvalid || !this._isRelative) {
        return;
      }
      parse.call(this, host, 'host');
    },

    get hostname() {
      return this._host;
    },
    set hostname(hostname) {
      if (this._isInvalid || !this._isRelative) {
        return;
      }
      parse.call(this, hostname, 'hostname');
    },

    get port() {
      return this._port;
    },
    set port(port) {
      if (this._isInvalid || !this._isRelative) {
        return;
      }
      parse.call(this, port, 'port');
    },

    get pathname() {
      return this._isInvalid ? '' : this._isRelative ?
          '/' + this._path.join('/') : this._schemeData;
    },
    set pathname(pathname) {
      if (this._isInvalid || !this._isRelative) {
        return;
      }
      this._path = [];
      parse.call(this, pathname, 'relative path start');
    },

    get search() {
      return this._isInvalid || !this._query || this._query === '?' ?
          '' : this._query;
    },
    set search(search) {
      if (this._isInvalid || !this._isRelative) {
        return;
      }
      this._query = '?';
      if (search[0] === '?') {
        search = search.slice(1);
      }
      parse.call(this, search, 'query');
    },

    get hash() {
      return this._isInvalid || !this._fragment || this._fragment === '#' ?
          '' : this._fragment;
    },
    set hash(hash) {
      if (this._isInvalid) {
        return;
      }
      this._fragment = '#';
      if (hash[0] === '#') {
        hash = hash.slice(1);
      }
      parse.call(this, hash, 'fragment');
    },

    get origin() {
      var host;
      if (this._isInvalid || !this._scheme) {
        return '';
      }
      // javascript: Gecko returns String(""), WebKit/Blink String("null")
      // Gecko throws error for "data://"
      // data: Gecko returns "", Blink returns "data://", WebKit returns "null"
      // Gecko returns String("") for file: mailto:
      // WebKit/Blink returns String("SCHEME://") for file: mailto:
      switch (this._scheme) {
        case 'data':
        case 'file':
        case 'javascript':
        case 'mailto':
          return 'null';
      }
      host = this.host;
      if (!host) {
        return '';
      }
      return this._scheme + '://' + host;
    }
  };

  // Copy over the static methods
  var OriginalURL = globalScope.URL;
  if (OriginalURL) {
    JURL.createObjectURL = function(blob) {
      // IE extension allows a second optional options argument.
      // http://msdn.microsoft.com/en-us/library/ie/hh772302(v=vs.85).aspx
      return OriginalURL.createObjectURL.apply(OriginalURL, arguments);
    };
    JURL.revokeObjectURL = function(url) {
      OriginalURL.revokeObjectURL(url);
    };
  }

  globalScope.URL = JURL;
})();

}

}));