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

Source/core/paint/GridPainter.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 GridPainter_h
 #define GridPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
 class LayoutPoint;
 class LayoutBox;
 class LayoutGrid;
 
 class GridPainter {
+    STACK_ALLOCATED();
 public:
     GridPainter(LayoutGrid& layoutGrid) : m_layoutGrid(layoutGrid) { }
 
     void paintChildren(const PaintInfo&, const LayoutPoint&);
 
 private:
     LayoutGrid& m_layoutGrid;
 };
 
 } // namespace blink
 
 #endif // GridPainter_h