Make classes and structures in core/paint fast-allocated.

Source/core/paint/BlockFlowPainter.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BlockFlowPainter_h
 #define BlockFlowPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 class LayoutPoint;
 struct PaintInfo;
 class LayoutBlockFlow;
 
 class BlockFlowPainter {
+    STACK_ALLOCATED();
 public:
     BlockFlowPainter(LayoutBlockFlow& layoutBlockFlow) : m_layoutBlockFlow(layoutBlockFlow) { }
     void paintFloats(const PaintInfo&, const LayoutPoint&, bool preservePhase);
     void paintSelection(const PaintInfo&, const LayoutPoint&);
 private:
     LayoutBlockFlow& m_layoutBlockFlow;
 };
 
 } // namespace blink
 
 #endif // BlockFlowPainter_h