ServiceWorker polyfill Fetch implementation.

Source/modules/serviceworkers/polyfills/cachePolyfill.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A simple, incomplete implementation of the Cache API, intended to facilitate
 // end to end serviceworker testing.
 
 // See https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#cache
 
 // FIXME: Support AbstractResponse/OpaqueResponse correctly.
@@ skipping 46 matching lines @@
                 that.entriesByMethod[request.method] = {};
             }
 
             var entriesByUrl = that.entriesByMethod[request.method];
             entriesByUrl[request.url] = response;
 
             resolve();
         });
     };
 
-    // FIXME: Implement this.
-    Cache.prototype.add = Promise.reject.bind(Promise, 'Cache.prototype.add() not implemented.');
+    Cache.prototype.add = function(request) {
+        var that = this;
+        request = _castToRequest(request);
+        return new Promise(function (resolve, reject) {
+            fetch(request).then(
+                function(response) {
+                    that.put(request, response).then(resolve);
+                },
+                reject);
+        });
+    };
 
     // FIXME: Add QueryParams argument.
     Cache.prototype.delete = function(request) {
         request = _castToRequest(request);
 
         var that = this;
         return new Promise(function(resolve, reject) {
             if (that.entriesByMethod.hasOwnProperty(request.method)) {
                 var entriesByUrl = that.entriesByMethod[request.method];
                 delete entriesByUrl[request.url];
@@ skipping 24 matching lines @@
             var entry = entriesByUrl[request.url];
             resolve(entry);
         });
     };
 
     // FIXME: Implement this.
     Cache.prototype.matchAll = Promise.reject.bind(Promise, 'Cache.prototype.matchAll not implemented.');
 
     global.Cache = global.Cache || Cache;
 }(self));  // window or worker global scope.