Replace our URL polyfill with the one from core-js

`core-js` polyfills have proven to be of good quality and using them
prevents us from having to maintain them ourselves.

src/display/api.js

@@ -20,7 +20,7 @@ import {
   InvalidPDFException, isArrayBuffer, isSameOrigin, MissingPDFException,
   NativeImageDecoding, PasswordException, setVerbosityLevel, shadow,
   stringToBytes, UnexpectedResponseException, UnknownErrorException,
-  unreachable, URL, warn
+  unreachable, warn
 } from '../shared/util';
 import {
   deprecated, DOMCanvasFactory, DOMCMapReaderFactory, DummyStatTimer,

src/display/display_utils.js

@@ -16,7 +16,7 @@
 
 import {
   assert, CMapCompressionType, isString, removeNullCharacters, stringToBytes,
-  unreachable, URL, Util, warn
+  unreachable, Util, warn
 } from '../shared/util';
 
 const DEFAULT_LINK_REL = 'noopener noreferrer nofollow';

src/pdf.js

@@ -107,7 +107,6 @@ exports.removeNullCharacters = pdfjsSharedUtil.removeNullCharacters;
 exports.shadow = pdfjsSharedUtil.shadow;
 exports.Util = pdfjsSharedUtil.Util;
 exports.ReadableStream = pdfjsSharedUtil.ReadableStream;
-exports.URL = pdfjsSharedUtil.URL;
 exports.RenderingCancelledException =
   pdfjsDisplayDisplayUtils.RenderingCancelledException;
 exports.getFilenameFromUrl = pdfjsDisplayDisplayUtils.getFilenameFromUrl;

src/shared/compatibility.js

@@ -208,6 +208,20 @@ const hasDOM = typeof window === 'object' && typeof document === 'object';
   globalScope.Promise = require('core-js/es/promise/index');
 })();
 
+// Support: IE
+(function checkURL() {
+  if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('IMAGE_DECODERS')) {
+    // The current image decoders don't use the `URL` constructor, so it
+    // doesn't need to be polyfilled for the IMAGE_DECODERS build target.
+    return;
+  }
+  if (typeof PDFJSDev !== 'undefined' && !PDFJSDev.test('GENERIC')) {
+    // The `URL` constructor is assumed to be available in the extension builds.
+    return;
+  }
+  globalScope.URL = require('core-js/web/url');
+})();
+
 // Support: IE<11, Safari<8, Chrome<36
 (function checkWeakMap() {
   if (globalScope.WeakMap) {

src/shared/url_polyfill.js

@@ -1,62 +0,0 @@
-/* Copyright 2018 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-restricted-globals */
-
-if (typeof PDFJSDev !== 'undefined' && !PDFJSDev.test('GENERIC')) {
-  // The `URL` constructor is assumed to be available in the extension builds.
-  exports.URL = URL;
-} else {
-  let isURLSupported = false;
-  try {
-    if (typeof URL === 'function' && typeof URL.prototype === 'object' &&
-        ('origin' in URL.prototype)) {
-      const u = new URL('b', 'http://a');
-      u.pathname = 'c%20d';
-      isURLSupported = (u.href === 'http://a/c%20d');
-    }
-  } catch (ex) {
-    // The `URL` constructor cannot be used.
-  }
-
-  if (isURLSupported) {
-    exports.URL = URL;
-  } else if (typeof PDFJSDev !== 'undefined' &&
-             PDFJSDev.test('IMAGE_DECODERS')) {
-    class DummyURL {
-      constructor() {
-        throw new Error('The current image decoders doesn\'t utilize the ' +
-                        '`URL` constructor, hence it shouldn\'t need to be ' +
-                        'polyfilled for the IMAGE_DECODERS build target.');
-      }
-    }
-    exports.URL = DummyURL;
-  } else {
-    const PolyfillURL = require('../../external/url/url-lib').URL;
-
-    // Attempt to copy over the static methods.
-    const OriginalURL = require('./global_scope').URL;
-    if (OriginalURL) {
-      PolyfillURL.createObjectURL = function(blob) {
-        // IE extension allows a second optional options argument, see
-        // http://msdn.microsoft.com/en-us/library/ie/hh772302(v=vs.85).aspx
-        return OriginalURL.createObjectURL.apply(OriginalURL, arguments);
-      };
-      PolyfillURL.revokeObjectURL = function(url) {
-        OriginalURL.revokeObjectURL(url);
-      };
-    }
-    exports.URL = PolyfillURL;
-  }
-}

src/shared/util.js

@@ -16,7 +16,6 @@
 
 import './compatibility';
 import { ReadableStream } from './streams_polyfill';
-import { URL } from './url_polyfill';
 
 const IDENTITY_MATRIX = [1, 0, 0, 1, 0, 0];
 const FONT_IDENTITY_MATRIX = [0.001, 0, 0, 0.001, 0, 0];
@@ -970,7 +969,6 @@ export {
   readUint32,
   removeNullCharacters,
   ReadableStream,
-  URL,
   setVerbosityLevel,
   shadow,
   string32,