MOBILE-3213 h5p: Send a resize event instead of a ready event

src/core/h5p/components/h5p-player/core-h5p-player.html

@@ -9,5 +9,5 @@
         <core-download-refresh [status]="state" [enabled]="canDownload" [loading]="calculating" [canTrustDownload]="true" (action)="download()"></core-download-refresh>
     </div>
 </div>
-<core-iframe *ngIf="showPackage" [src]="playerSrc" iframeHeight="auto" [allowFullscreen]="true" (loaded)="sendHello($event)"></core-iframe>
+<core-iframe *ngIf="showPackage" [src]="playerSrc" iframeHeight="auto" [allowFullscreen]="true" (loaded)="iframeLoaded()"></core-iframe>
 <script *ngIf="resizeScript && showPackage" type="text/javascript" [src]="resizeScript"></script>

src/core/h5p/components/h5p-player/h5p-player.ts

@@ -269,17 +269,11 @@ export class CoreH5PPlayerComponent implements OnInit, OnChanges, OnDestroy {
     }
 
     /**
-     * Send hello to the H5P iframe.
-     *
-     * @param iframe The iframe.
+     * H5P iframe has been loaded.
      */
-    sendHello(iframe?: HTMLIFrameElement): void {
-        const ready = {
-            context: 'h5p',
-            action: 'ready'
-        };
-
-        iframe.contentWindow.postMessage(ready, '*');
+    iframeLoaded(): void {
+        // Send a resize event to the window so H5P package recalculates the size.
+        window.dispatchEvent(new Event('resize'));
     }
 
     /**