feat: deprecate @angular/http in favor of @angular/common/http (#18906)

As of 5.0, @angular/http is deprecated. @angular/common/http will
be the official HTTP API in Angular going forward.

PR Close #18906

packages/common/http/testing/src/api.ts

@@ -13,7 +13,7 @@ import {TestRequest} from './request';
 /**
  * Defines a matcher for requests based on URL, method, or both.
  *
- * @experimental
+ * @stable
  */
 export interface RequestMatch {
   method?: string;
@@ -24,7 +24,7 @@ export interface RequestMatch {
  * Controller to be injected into tests, that allows for mocking and flushing
  * of requests.
  *
- * @experimental
+ * @stable
  */
 export abstract class HttpTestingController {
   /**