refactor(core): remove @Injectable as only classes that are instantiated via DI need it

modules/angular2/src/core/change_detection/differs/iterable_differs.ts

@@ -31,7 +31,6 @@ export interface IterableDifferFactory {
 /**
  * A repository of different iterable diffing strategies used by NgFor, NgClass, and others.
  */
-@Injectable()
 @CONST()
 export class IterableDiffers {
   constructor(public factories: IterableDifferFactory[]) {}

modules/angular2/src/core/change_detection/differs/keyvalue_differs.ts

@@ -23,7 +23,6 @@ export interface KeyValueDifferFactory {
 /**
  * A repository of different Map diffing strategies used by NgClass, NgStyle, and others.
  */
-@Injectable()
 @CONST()
 export class KeyValueDiffers {
   constructor(public factories: KeyValueDifferFactory[]) {}

modules/angular2/src/platform/worker_render.dart

@@ -59,7 +59,6 @@ class UIMessageBusSource extends IsolateMessageBusSource {
  * Wrapper class that exposes the Isolate
  * and underlying {@link MessageBus} for lower level message passing.
  */
-@Injectable()
 class WebWorkerInstance {
   Isolate worker;
   MessageBus bus;