refactor(EventEmitter): rename .next() to .emit()

BREAKING CHANGE:

EventEmitter#next(value) is deprecated, use EventEmitter#emit(value)
instead.

Closes #4287

Closes #5302

modules/angular2/src/web_workers/ui/event_dispatcher.ts

@@ -101,7 +101,7 @@ export class EventDispatcher implements RenderEventDispatcher {
     var serializedLocals = StringMapWrapper.create();
     StringMapWrapper.set(serializedLocals, '$event', serializedEvent);
 
-    ObservableWrapper.callNext(this._sink, {
+    ObservableWrapper.callEmit(this._sink, {
       "viewRef": this._serializer.serialize(this._viewRef, RenderViewRef),
       "elementIndex": elementIndex,
       "eventName": eventName,

modules/angular2/src/web_workers/ui/setup.ts

@@ -20,7 +20,7 @@ export class WebWorkerSetup {
 
     ObservableWrapper.subscribe(source, (message: string) => {
       if (StringWrapper.equals(message, "ready")) {
-        ObservableWrapper.callNext(sink, {"rootUrl": this.rootUrl});
+        ObservableWrapper.callEmit(sink, {"rootUrl": this.rootUrl});
       }
     });
   }