refactor(TypeScript): Add noImplicitAny

We automatically insert explicit 'any's where needed. These need to be
addressed as in #9100.

Fixes #4924

modules/playground/src/key_events/index.ts

@@ -18,12 +18,12 @@ class KeyEventsApp {
   lastKey: string = '(none)';
   shiftEnter: boolean = false;
 
-  onKeyDown(event): void {
+  onKeyDown(event: any /** TODO #9100 */): void {
     this.lastKey = KeyEventsPlugin.getEventFullKey(event);
     event.preventDefault();
   }
 
-  onShiftEnter(event): void {
+  onShiftEnter(event: any /** TODO #9100 */): void {
     this.shiftEnter = true;
     event.preventDefault();
   }