Fix progress bar regression on Mac

Source/platform/mac/LocalCurrentGraphicsContext.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 26 matching lines @@
     ~LocalCurrentGraphicsContext();
     CGContextRef cgContext();
 private:
 
     GraphicsContext* m_savedGraphicsContext;
     NSGraphicsContext* m_savedNSGraphicsContext;
     bool m_didSetGraphicsContext;
     gfx::SkiaBitLocker m_skiaBitLocker;
 };
 
-class PLATFORM_EXPORT ContextContainer {
-    WTF_MAKE_NONCOPYABLE(ContextContainer);
-public:
-    ContextContainer(GraphicsContext*, IntRect clipRect);
-
-    // This synchronizes the CGContext to reflect the current SkCanvas state.
-    // The implementation may not return the same CGContext each time.
-    CGContextRef context() { return m_skiaBitLocker.cgContext(); }
-
-private:
-    gfx::SkiaBitLocker m_skiaBitLocker;
-};
-
 }