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/src/xsrf.ts

@@ -21,7 +21,7 @@ export const XSRF_HEADER_NAME = new InjectionToken<string>('XSRF_HEADER_NAME');
 /**
  * Retrieves the current XSRF token to use with the next outgoing request.
  *
- * @experimental
+ * @stable
  */
 export abstract class HttpXsrfTokenExtractor {
   /**