refactor(change_detection): generate handleEvent only when necessary

modules/angular2/test/change_detection/change_detector_spec.ts

@@ -899,6 +899,7 @@ export function main() {
           res = val.changeDetector.handleEvent("event", 0, locals);
           expect(res).toBe(false);
         });
+
       });
     });
   });

modules/angular2/test/transform/integration/two_annotations_files/expected/bar.ng_deps.dart

@@ -36,11 +36,6 @@ class _MyComponent_ChangeDetector0
     dehydrateDirectives(false);
   }
 
-  bool handleEvent(eventName, elIndex, locals) {
-    var preventDefault = false;
-    return preventDefault;
-  }
-
   void detectChangesInRecordsInternal(throwOnChange) {
     var l_context = this.context, l_myNum0, c_myNum0, l_interpolate1;
     c_myNum0 = false;