refactor(platform-browser): ensure compatibility with noImplicitOverride (#42512)

Adds the `override` keyword to the `platform-browser` sources to ensure
compatibility with `noImplicitOverride`.

PR Close #42512

packages/platform-browser/animations/src/animation_renderer.ts

@@ -241,7 +241,7 @@ export class AnimationRenderer extends BaseAnimationRenderer implements Renderer
     this.namespaceId = namespaceId;
   }
 
-  setProperty(el: any, name: string, value: any): void {
+  override setProperty(el: any, name: string, value: any): void {
     if (name.charAt(0) == ANIMATION_PREFIX) {
       if (name.charAt(1) == '.' && name == DISABLE_ANIMATIONS_FLAG) {
         value = value === undefined ? true : !!value;
@@ -254,8 +254,9 @@ export class AnimationRenderer extends BaseAnimationRenderer implements Renderer
     }
   }
 
-  listen(target: 'window'|'document'|'body'|any, eventName: string, callback: (event: any) => any):
+  override listen(
-      () => void {
+      target: 'window'|'document'|'body'|any, eventName: string,
+      callback: (event: any) => any): () => void {
     if (eventName.charAt(0) == ANIMATION_PREFIX) {
       const element = resolveElementFromTarget(target);
       let name = eventName.substr(1);

packages/platform-browser/animations/test/animation_renderer_spec.ts

@@ -368,26 +368,26 @@ class MockAnimationEngine extends InjectableAnimationEngine {
     data.push(args);
   }
 
-  registerTrigger(
+  override registerTrigger(
       componentId: string, namespaceId: string, hostElement: any, name: string,
       metadata: AnimationTriggerMetadata): void {
     this.triggers.push(metadata);
   }
 
-  onInsert(namespaceId: string, element: any): void {
+  override onInsert(namespaceId: string, element: any): void {
     this._capture('onInsert', [element]);
   }
 
-  onRemove(namespaceId: string, element: any, domFn: () => any): void {
+  override onRemove(namespaceId: string, element: any, domFn: () => any): void {
     this._capture('onRemove', [element]);
   }
 
-  process(namespaceId: string, element: any, property: string, value: any): boolean {
+  override process(namespaceId: string, element: any, property: string, value: any): boolean {
     this._capture('setProperty', [element, property, value]);
     return true;
   }
 
-  listen(
+  override listen(
       namespaceId: string, element: any, eventName: string, eventPhase: string,
       callback: (event: any) => any): () => void {
     // we don't capture the callback here since the renderer wraps it in a zone
@@ -395,21 +395,21 @@ class MockAnimationEngine extends InjectableAnimationEngine {
     return () => {};
   }
 
-  flush() {}
+  override flush() {}
 
-  destroy(namespaceId: string) {}
+  override destroy(namespaceId: string) {}
 }
 
 @Injectable()
 class ExtendedAnimationRendererFactory extends AnimationRendererFactory {
   public log: string[] = [];
 
-  begin() {
+  override begin() {
     super.begin();
     this.log.push('begin');
   }
 
-  end() {
+  override end() {
     super.end();
     this.log.push('end');
   }

packages/platform-browser/src/dom/dom_renderer.ts

@@ -304,7 +304,7 @@ class EmulatedEncapsulationDomRenderer2 extends DefaultDomRenderer2 {
     super.setAttribute(element, this.hostAttr, '');
   }
 
-  createElement(parent: any, name: string): Element {
+  override createElement(parent: any, name: string): Element {
     const el = super.createElement(parent, name);
     super.setAttribute(el, this.contentAttr, '');
     return el;
@@ -332,20 +332,20 @@ class ShadowDomRenderer extends DefaultDomRenderer2 {
     return node === this.hostEl ? this.shadowRoot : node;
   }
 
-  destroy() {
+  override destroy() {
     this.sharedStylesHost.removeHost(this.shadowRoot);
   }
 
-  appendChild(parent: any, newChild: any): void {
+  override appendChild(parent: any, newChild: any): void {
     return super.appendChild(this.nodeOrShadowRoot(parent), newChild);
   }
-  insertBefore(parent: any, newChild: any, refChild: any): void {
+  override insertBefore(parent: any, newChild: any, refChild: any): void {
     return super.insertBefore(this.nodeOrShadowRoot(parent), newChild, refChild);
   }
-  removeChild(parent: any, oldChild: any): void {
+  override removeChild(parent: any, oldChild: any): void {
     return super.removeChild(this.nodeOrShadowRoot(parent), oldChild);
   }
-  parentNode(node: any): any {
+  override parentNode(node: any): any {
     return this.nodeOrShadowRoot(super.parentNode(this.nodeOrShadowRoot(node)));
   }
 }

packages/platform-browser/src/dom/shared_styles_host.ts

@@ -64,7 +64,7 @@ export class DomSharedStylesHost extends SharedStylesHost implements OnDestroy {
     this._hostNodes.delete(hostNode);
   }
 
-  onStylesAdded(additions: Set<string>): void {
+  override onStylesAdded(additions: Set<string>): void {
     this._hostNodes.forEach((styleNodes, hostNode) => {
       this._addStylesToHost(additions, hostNode, styleNodes);
     });

packages/platform-browser/test/dom/events/event_manager_spec.ts

@@ -526,10 +526,10 @@ class FakeNgZone extends NgZone {
   constructor() {
     super({enableLongStackTrace: false, shouldCoalesceEventChangeDetection: true});
   }
-  run<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any[]): T {
+  override run<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any[]): T {
     return fn();
   }
-  runOutsideAngular(fn: Function) {
+  override runOutsideAngular(fn: Function) {
     return fn();
   }
 }

packages/platform-browser/test/testing_public_spec.ts

@@ -70,7 +70,7 @@ class FancyService {
 }
 
 class MockFancyService extends FancyService {
-  value: string = 'mocked out value';
+  override value: string = 'mocked out value';
 }
 
 @Component({