fix(url): Add CustomEvent polyfill for IE

Closes ui-router/angular#154
Closes #64
Closes ui-router/react#62
Closes ui-router/angular#139
Closes ui-router/angular#153

Author: christopherthielen

src/vanilla/baseLocationService.ts

@@ -7,9 +7,12 @@ import { LocationServices } from "../common/coreservices";
 import { Disposable } from "../interface";
 import { UIRouter } from "../router";
 import { LocationLike, HistoryLike } from "./interface";
-import { parseUrl, getParams, buildUrl } from "./utils";
+import { parseUrl, getParams, buildUrl, getCustomEventCtor } from "./utils";
 import { isDefined } from "../common/predicates";
 import { extend, deregAll, removeFrom } from "../common/common";
+
+const Evt: typeof CustomEvent = getCustomEventCtor();
+
 /** A base `LocationServices` */
 export abstract class BaseLocationServices implements LocationServices, Disposable {
   constructor(router: UIRouter, public fireAfterUpdate: boolean) {
@@ -59,7 +62,7 @@ export abstract class BaseLocationServices implements LocationServices, Disposab
       this._set(null, null, url, replace);
 
       if (this.fireAfterUpdate) {
-        let evt = extend(new Event("locationchange"), { url });
+        let evt = extend(new Evt("locationchange"), { url });
         this._listeners.forEach(cb => cb(evt));
       }
     }

src/vanilla/utils.ts

@@ -78,3 +78,20 @@ export function locationPluginFactory(
   };
 }
 
+export function getCustomEventCtor(): typeof CustomEvent {
+  // CustomEvent Polyfill
+  function _CustomEvent(event, params) {
+    params = params || { bubbles: false, cancelable: false, detail: undefined };
+    let evt = document.createEvent( 'CustomEvent' );
+    evt.initCustomEvent( event, params.bubbles, params.cancelable, params.detail );
+    return evt;
+  }
+  _CustomEvent.prototype = Event.prototype;
+
+  try {
+    new CustomEvent('foo');
+    return CustomEvent;
+  } catch (_err) {
+    return _CustomEvent as any;
+  }
+}