Replace `value === (value | 0)` checks with `Number.isInteger(value)` in the `web/` folder

Rather than doing what (at first) may seem like a fairly obscure comparison, using `Number.isInteger` will clearly indicate the intent of the code.

web/pdf_link_service.js

@@ -98,7 +98,7 @@ class PDFLinkService {
           });
           return;
         }
-      } else if ((destRef | 0) === destRef) { // Integer
+      } else if (Number.isInteger(destRef)) {
         pageNumber = destRef + 1;
       } else {
         console.error(`PDFLinkService.navigateTo: "${destRef}" is not ` +
@@ -359,9 +359,8 @@ function isValidExplicitDestination(dest) {
   }
   let page = dest[0];
   if (!(typeof page === 'object' &&
-        typeof page.num === 'number' && (page.num | 0) === page.num &&
+        Number.isInteger(page.num) && Number.isInteger(page.gen)) &&
-        typeof page.gen === 'number' && (page.gen | 0) === page.gen) &&
+      !(Number.isInteger(page) && page >= 0)) {
-      !(typeof page === 'number' && (page | 0) === page && page >= 0)) {
     return false;
   }
   let zoom = dest[1];

web/pdf_viewer.js

@@ -159,7 +159,7 @@ class PDFViewer {
    * @param {number} val - The page number.
    */
   set currentPageNumber(val) {
-    if ((val | 0) !== val) { // Ensure that `val` is an integer.
+    if (!Number.isInteger(val)) {
       throw new Error('Invalid page number.');
     }
     if (!this.pdfDocument) {

web/preferences.js

@@ -141,7 +141,7 @@ class BasePreferences {
                           `expected a ${defaultType}.`);
         }
       } else {
-        if (valueType === 'number' && (value | 0) !== value) {
+        if (valueType === 'number' && !Number.isInteger(value)) {
           throw new Error(`Set preference: "${value}" must be an integer.`);
         }
       }