2D Canvas: Refactor code re-attempting to allocate an imageBuffer.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 103 matching lines @@
 
 CanvasRenderingContext2D::~CanvasRenderingContext2D()
 {
 #if !ASSERT_DISABLED
     unwindStateStack();
 #endif
 }
 
 bool CanvasRenderingContext2D::isAccelerated() const
 {
-    if (!canvas()->hasCreatedImageBuffer())
+    if (!canvas()->existingDrawingContext())
         return false;
     GraphicsContext* context = drawingContext();
     return context && context->isAccelerated();
 }
 
 void CanvasRenderingContext2D::reset()
 {
     unwindStateStack();
     m_stateStack.resize(1);
     m_stateStack.first() = State();
@@ skipping 2297 matching lines @@
     const int focusRingWidth = 5;
     const int focusRingOutline = 0;
     c->drawFocusRing(path, focusRingWidth, focusRingOutline, focusRingColor);
 
     c->restore();
 
     didDraw(dirtyRect);
 }
 
 } // namespace WebCore