Fixes lint warning W018: confusing use of exclamation mark

src/shared/annotation.js

@@ -112,7 +112,7 @@ var Annotation = (function AnnotationClosure() {
           var isInvalid = false;
           var numPositive = 0;
           for (var i = 0; i < dashArrayLength; i++) {
-            if (!(+dashArray[i] >= 0)) {
+            if (+dashArray[i] < 0) {
               isInvalid = true;
               break;
             } else if (dashArray[i] > 0) {

test/reporter.js

@@ -29,7 +29,6 @@ module.exports = {
 
       switch (err.code) {
         case 'W004': // variable is already defined
-        case 'W018': // confusing use of !
           break;
         default:
           len++;

web/page_view.js

@@ -348,7 +348,7 @@ var PageView = function pageView(container, id, scale,
 
     var x = 0, y = 0;
     var width = 0, height = 0, widthScale, heightScale;
-    var changeOrientation = !!(this.rotation % 180);
+    var changeOrientation = (this.rotation % 180 === 0 ? false : true);
     var pageWidth = (changeOrientation ? this.height : this.width) /
       this.scale / CSS_UNITS;
     var pageHeight = (changeOrientation ? this.width : this.height) /