Add correct type to TestBed.createView

Closes angular#1727

Author: matanlurey

modules/angular2/src/test_lib/test_bed.js

@@ -74,8 +74,7 @@ export class TestBed {
    * @return {Promise<ViewProxy>}
    */
   createView(component: Type,
-             {context = null, html = null}: {context:any, html: string} = {}): Promise<AppView> {
-
+             {context = null, html = null}: {context:any, html: string} = {}): Promise<ViewProxy> {
     if (isBlank(component) && isBlank(context)) {
       throw new BaseException('You must specified at least a component or a context');
     }