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

Source/core/paint/RootInlineBoxPainter.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 RootInlineBoxPainter_h
 #define RootInlineBoxPainter_h
 
+#include "wtf/Allocator.h"
+
 namespace blink {
 
 struct PaintInfo;
 class LayoutPoint;
 class LayoutUnit;
 class RootInlineBox;
 
 class RootInlineBoxPainter {
+    STACK_ALLOCATED();
 public:
     RootInlineBoxPainter(RootInlineBox& rootInlineBox) : m_rootInlineBox(rootInlineBox) { }
 
     void paint(const PaintInfo&, const LayoutPoint&, LayoutUnit lineTop, LayoutUnit lineBottom);
 
 private:
     void paintEllipsisBox(const PaintInfo&, const LayoutPoint& paintOffset, LayoutUnit lineTop, LayoutUnit lineBottom) const;
 
     RootInlineBox& m_rootInlineBox;
 };
 
 } // namespace blink
 
 #endif // RootInlineBoxPainter_h