Stop pretending MediaControls::initializeControls() will fail

Source/core/html/shadow/MediaControls.h

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 59 matching lines @@
 
     void updateTextTrackDisplay();
 
     void mediaElementFocused();
 
     virtual void trace(Visitor*) override;
 
 private:
     explicit MediaControls(HTMLMediaElement&);
 
-    bool initializeControls();
+    void initializeControls();
 
     void makeOpaque();
     void makeTransparent();
 
     void updatePlayState();
 
     enum HideBehaviorFlags {
         IgnoreVideoHover = 1 << 0,
         IgnoreFocus = 1 << 1,
         IgnoreControlsHover = 1 << 2
@@ skipping 46 matching lines @@
     bool m_isMouseOverControls : 1;
     bool m_isPausedForScrubbing : 1;
     bool m_wasLastEventTouch : 1;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());
 
 }
 
 #endif