Introduce DEFINE_RENDER_OBJECT_TYPE_CASTS to replace manual toRenderFoo, and use it

Source/core/rendering/RenderMultiColumnBlock.h

 /*
  * Copyright (C) 2012 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 57 matching lines @@
     void ensureColumnSets();
 
     RenderMultiColumnFlowThread* m_flowThread;
     unsigned m_columnCount;   // The default column count/width that are based off our containing block width. These values represent only the default,
     LayoutUnit m_columnWidth; // since a multi-column block that is split across variable width pages or regions will have different column counts and widths in each.
                               // These values will be cached (eventually) for multi-column blocks.
     LayoutUnit m_columnHeightAvailable; // Total height available to columns, or 0 if auto.
     bool m_inBalancingPass; // Set when relayouting for column balancing.
 };
 
-inline RenderMultiColumnBlock* toRenderMultiColumnBlock(RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderMultiColumnBlock());
-    return static_cast<RenderMultiColumnBlock*>(object);
-}
-
-inline const RenderMultiColumnBlock* toRenderMultiColumnBlock(const RenderObject* object)
-{
-    ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderMultiColumnBlock());
-    return static_cast<const RenderMultiColumnBlock*>(object);
-}
-
-// This will catch anyone doing an unnecessary cast.
-void toRenderMultiColumnBlock(const RenderMultiColumnBlock*);
+DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderMultiColumnBlock, isRenderMultiColumnBlock());
 
 } // namespace WebCore
 
 #endif // RenderMultiColumnBlock_h