refactor(change_detection): introduce enum ChangeDetectionStrategy

BREAKING CHANGE

Closes #2497

- change detection strategy type changes from string to ChangeDetectionStrategy
- CHECK_ONCE => ChangeDetectionStrategy.CheckOnce
- CHECKED => ChangeDetectionStrategy.Checked
- CHECK_ALWAYS => ChangeDetectionStrategy.CheckAlways
- DETACHED => ChangeDetectionStrategy.Detached
- ON_PUSH => ChangeDetectionStrategy.OnPush
- DEFAULT => ChangeDetectionStrategy.Default
- ON_PUSH_OBSERVE => ChangeDetectionStrategy.OnPushObserve

modules/angular2/src/core/metadata.ts

@@ -33,6 +33,7 @@ import {
 } from './metadata/directives';
 
 import {ViewMetadata, ViewEncapsulation} from './metadata/view';
+import {ChangeDetectionStrategy} from 'angular2/src/core/change_detection/change_detection';
 
 import {makeDecorator, makeParamDecorator, TypeDecorator, Class} from './util/decorators';
 import {Type} from 'angular2/src/core/facade/lang';
@@ -191,7 +192,7 @@ export interface ComponentFactory {
     exportAs?: string,
     compileChildren?: boolean,
     viewBindings?: List<any>,
-    changeDetection?: string,
+    changeDetection?: ChangeDetectionStrategy,
   }): ComponentDecorator;
   new (obj: {
     selector?: string,
@@ -203,7 +204,7 @@ export interface ComponentFactory {
     exportAs?: string,
     compileChildren?: boolean,
     viewBindings?: List<any>,
-    changeDetection?: string,
+    changeDetection?: ChangeDetectionStrategy,
   }): ComponentMetadata;
 }