Use ::-internal-media-controls* instead of ::-webkit-media-controls*

LayoutTests/media/media-controls.js

 var captionsButtonElement;
 var captionsButtonCoordinates;
 
 // As specified in mediaControls.css, this is how long it takes to fade out controls
 const controlsFadeOutDurationMs = 300;
 
 // The timeout for the hide-after-no-mouse-movement behavior. Defined (and
 // should mirror) the value 'timeWithoutMouseMovementBeforeHidingMediaControls'
 // in MediaControls.cpp.
 const controlsMouseMovementTimeoutMs = 3000;
@@ skipping 13 matching lines @@
             if (childElement)
                 return childElement;
         }
     }
 
     return null;
 }
 
 function mediaControlsButton(element, id)
 {
-    var controlID = "-webkit-media-controls-" + id;
+    var controlID = "-internal-media-controls-" + id;
     var button = mediaControlsElement(internals.shadowRoot(element).firstChild, controlID);
     if (!button)
         throw "Failed to find media control element ID '" + id + "'";
     return button;
 }
 
 function mediaControlsButtonCoordinates(element, id)
 {
     var button = mediaControlsButton(element, id);
     var buttonBoundingRect = button.getBoundingClientRect();
@@ skipping 81 matching lines @@
     // Compute the time it'll take until the controls will be invisible -
     // assuming playback has been started prior to invoking this
     // function. Allow 500ms slack.
     var hideTimeoutMs = controlsMouseMovementTimeoutMs + controlsFadeOutDurationMs + 500;
 
     if (!mediaElement.loop && hideTimeoutMs >= 1000 * (mediaElement.duration - mediaElement.currentTime))
         throw "The media will end before the controls have been hidden";
 
     setTimeout(func, hideTimeoutMs);
 }