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

Source/core/layout/GapRects.h

 /*
     Copyright (C) 2005, 2006 Apple Inc. 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.
 
 
     Some useful definitions needed for laying out elements
 */
 
 #ifndef GapRects_h
 #define GapRects_h
 
 #include "platform/geometry/LayoutRect.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
 struct GapRects {
+    STACK_ALLOCATED();
     const LayoutRect& left() const { return m_left; }
     const LayoutRect& center() const { return m_center; }
     const LayoutRect& right() const { return m_right; }
 
     void uniteLeft(const LayoutRect& r) { m_left.unite(r); }
     void uniteCenter(const LayoutRect& r) { m_center.unite(r); }
     void uniteRight(const LayoutRect& r) { m_right.unite(r); }
     void unite(const GapRects& o) { uniteLeft(o.left()); uniteCenter(o.center()); uniteRight(o.right()); }
 
     operator LayoutRect() const
@@ skipping 12 matching lines @@
 
 private:
     LayoutRect m_left;
     LayoutRect m_center;
     LayoutRect m_right;
 };
 
 } // namespace blink
 
 #endif // GapRects_h