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

Source/core/layout/svg/SVGTextLayoutEngineSpacing.h

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef SVGTextLayoutEngineSpacing_h
 #define SVGTextLayoutEngineSpacing_h
 
+#include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/Unicode.h"
 
 namespace blink {
 
 class Font;
 
 // Helper class used by SVGTextLayoutEngine to handle 'letter-spacing' and 'word-spacing'.
 class SVGTextLayoutEngineSpacing {
+    STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(SVGTextLayoutEngineSpacing);
 public:
     SVGTextLayoutEngineSpacing(const Font&, float effectiveZoom);
 
     float calculateCSSSpacing(UChar currentCharacter);
 
 private:
     const Font& m_font;
     UChar m_lastCharacter;
     float m_effectiveZoom;
 };
 
 } // namespace blink
 
 #endif