Introduce toHTMLCanvasElement

Source/core/rendering/RenderHTMLCanvas.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 31 matching lines @@
     : RenderReplaced(element, element->size())
 {
     view()->frameView()->setIsVisuallyNonEmpty();
 }
 
 bool RenderHTMLCanvas::requiresLayer() const
 {
     if (RenderReplaced::requiresLayer())
         return true;
     
-    HTMLCanvasElement* canvas = static_cast<HTMLCanvasElement*>(node());
+    HTMLCanvasElement* canvas = toHTMLCanvasElement(node());
     return canvas && canvas->renderingContext() && canvas->renderingContext()->isAccelerated();
 }
 
 void RenderHTMLCanvas::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     LayoutRect rect = contentBoxRect();
     rect.moveBy(paintOffset);
 
     if (Frame* frame = this->frame()) {
         if (Page* page = frame->page()) {
             if (paintInfo.phase == PaintPhaseForeground)
                 page->addRelevantRepaintedObject(this, rect);
         }
     }
 
     bool useLowQualityScale = style()->imageRendering() == ImageRenderingOptimizeContrast;
-    static_cast<HTMLCanvasElement*>(node())->paint(paintInfo.context, rect, useLowQualityScale);
+    toHTMLCanvasElement(node())->paint(paintInfo.context, rect, useLowQualityScale);
 }
 
 void RenderHTMLCanvas::canvasSizeChanged()
 {
-    IntSize canvasSize = static_cast<HTMLCanvasElement*>(node())->size();
+    IntSize canvasSize = toHTMLCanvasElement(node())->size();
     LayoutSize zoomedSize(canvasSize.width() * style()->effectiveZoom(), canvasSize.height() * style()->effectiveZoom());
 
     if (zoomedSize == intrinsicSize())
         return;
 
     setIntrinsicSize(zoomedSize);
 
     if (!parent())
         return;
 
     if (!preferredLogicalWidthsDirty())
         setPreferredLogicalWidthsDirty(true);
 
     LayoutSize oldSize = size();
     updateLogicalWidth();
     updateLogicalHeight();
     if (oldSize == size())
         return;
 
     if (!selfNeedsLayout())
         setNeedsLayout(true);
 }
 
 } // namespace WebCore