Replace static_cast with safe casting methods

Source/core/rendering/style/StylePendingImage.h

 /*
  * Copyright (C) 2010 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 25 matching lines @@
 namespace WebCore {
 
 // StylePendingImage is a placeholder StyleImage that is entered into the RenderStyle during
 // style resolution, in order to avoid loading images that are not referenced by the final style.
 // They should never exist in a RenderStyle after it has been returned from the style selector.
 
 class StylePendingImage : public StyleImage {
 public:
     static PassRefPtr<StylePendingImage> create(CSSValue* value) { return adoptRef(new StylePendingImage(value)); }
 
-    virtual WrappedImagePtr data() const { return static_cast<CSSImageValue*>(m_value); }
+    virtual WrappedImagePtr data() const { return toCSSImageValue(m_value); }
 
     virtual PassRefPtr<CSSValue> cssValue() const { return m_value; }
-    CSSImageValue* cssImageValue() const { return m_value->isImageValue() ? static_cast<CSSImageValue*>(m_value) : 0; }
+    CSSImageValue* cssImageValue() const { return m_value->isImageValue() ? toCSSImageValue(m_value) : 0; }
     CSSImageGeneratorValue* cssImageGeneratorValue() const { return m_value->isImageGeneratorValue() ? static_cast<CSSImageGeneratorValue*>(m_value) : 0; }
     CSSCursorImageValue* cssCursorImageValue() const { return m_value->isCursorImageValue() ? static_cast<CSSCursorImageValue*>(m_value) : 0; }
     CSSImageSetValue* cssImageSetValue() const { return m_value->isImageSetValue() ? static_cast<CSSImageSetValue*>(m_value) : 0; }
 
     virtual LayoutSize imageSize(const RenderObject*, float /*multiplier*/) const OVERRIDE { return LayoutSize(); }
     virtual bool imageHasRelativeWidth() const { return false; }
     virtual bool imageHasRelativeHeight() const { return false; }
     virtual void computeIntrinsicDimensions(const RenderObject*, Length& /* intrinsicWidth */ , Length& /* intrinsicHeight */, FloatSize& /* intrinsicRatio */) { }
     virtual bool usesImageContainerSize() const { return false; }
     virtual void setContainerSizeForRenderer(const RenderObject*, const IntSize&, float) { }
@@ skipping 11 matching lines @@
         : m_value(value)
     {
         m_isPendingImage = true;
     }
 
     CSSValue* m_value; // Not retained; it owns us.
 };
 
 }
 #endif