Bug 1621166 - part2 : do not stop media control for media being used in PIP mode. r=MeFisto94

The media element being used in the PIP mode would always display on the screen even if the the tab it belongs to is in the background, so users would have high chance to interact with it again. Therefore, we don't want to start a stop-timer to cancel media control for that element.

Differential Revision: https://phabricator.services.mozilla.com/D67381

dom/html/HTMLVideoElement.cpp

@@ -582,6 +582,8 @@ void HTMLVideoElement::EndCloningVisually() {
   Unused << mVisualCloneTarget->SetVisualCloneSource(nullptr);
   Unused << SetVisualCloneTarget(nullptr);
 
+  CreateStopMediaControlTimerIfNeeded();
+
   if (IsInComposedDoc() && !StaticPrefs::media_cloneElementVisually_testing()) {
     NotifyUAWidgetSetupOrChange();
   }