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/facade/async.dart

@@ -46,9 +46,14 @@ class ObservableWrapper {
     s.cancel();
   }
 
+  @Deprecated('Use callEmit() instead')
   static void callNext(EventEmitter emitter, value) {
     emitter.add(value);
   }
+  
+  static void callEmit(EventEmitter emitter, value) {
+    emitter.add(value);
+  }
 
   static void callError(EventEmitter emitter, error) {
     emitter.addError(error);
@@ -85,6 +90,10 @@ class EventEmitter<T> extends Stream<T> {
   void add(value) {
     _controller.add(value);
   }
+  
+  void emit(value) {
+    _controller.add(value);
+  }
 
   void addError(error) {
     _controller.addError(error);