Introduce toHTMLCanvasElement

Source/core/rendering/RenderHTMLCanvas.cpp

Index: Source/core/rendering/RenderHTMLCanvas.cpp
diff --git a/Source/core/rendering/RenderHTMLCanvas.cpp b/Source/core/rendering/RenderHTMLCanvas.cpp
index 8a183bf87a7168c2494f33b5103132c2b3ab8f5a..5101e8f9f0c29e3bcaf18cc27e1a0ce0b22a9b17 100644
--- a/Source/core/rendering/RenderHTMLCanvas.cpp
+++ b/Source/core/rendering/RenderHTMLCanvas.cpp
@@ -49,7 +49,7 @@ 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();
 }
 
@@ -66,12 +66,12 @@ void RenderHTMLCanvas::paintReplaced(PaintInfo& paintInfo, const LayoutPoint& pa
     }
 
     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())