build(bazel): Turning on strictPropertyInitialization for Angular. (#24572)

All errors for existing fields have been detected and suppressed with a
`!` assertion.

Issue/24571 is tracking proper clean up of those instances.

One-line change required in ivy/compilation.ts, because it appears that
the new syntax causes tsickle emitted node to no longer track their
original sourceFiles.

PR Close #24572

packages/http/src/backends/jsonp_backend.ts

@@ -26,15 +26,18 @@ const JSONP_ERR_WRONG_METHOD = 'JSONP requests must use GET request method.';
  * @deprecated see https://angular.io/guide/http
  */
 export class JSONPConnection implements Connection {
-  private _id: string;
-  private _script: Element;
+  // TODO(issue/24571): remove '!'.
+  private _id !: string;
+  // TODO(issue/24571): remove '!'.
+  private _script !: Element;
   private _responseData: any;
   private _finished: boolean = false;
 
   /**
    * The {@link ReadyState} of this request.
    */
-  readyState: ReadyState;
+  // TODO(issue/24571): remove '!'.
+  readyState !: ReadyState;
 
   /**
    * The outgoing HTTP request.

packages/http/src/backends/xhr_backend.ts

@@ -37,7 +37,8 @@ export class XHRConnection implements Connection {
    * `XMLHttpRequest`.
    */
   response: Observable<Response>;
-  readyState: ReadyState;
+  // TODO(issue/24571): remove '!'.
+  readyState !: ReadyState;
   constructor(req: Request, browserXHR: BrowserXhr, baseResponseOptions?: ResponseOptions) {
     this.request = req;
     this.response = new Observable<Response>((responseObserver: Observer<Response>) => {