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

Source/core/layout/line/TrailingObjects.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2014 Adobe Systems Inc.
  *
  * 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 TrailingObjects_h
 #define TrailingObjects_h
 
 #include "core/layout/api/LineLayoutItem.h"
 #include "core/layout/api/LineLayoutText.h"
+#include "wtf/Allocator.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class InlineIterator;
 
 struct BidiRun;
 
 template <class Iterator, class Run> class BidiResolver;
 template <class Iterator> class MidpointState;
 typedef BidiResolver<InlineIterator, BidiRun> InlineBidiResolver;
 typedef MidpointState<InlineIterator> LineMidpointState;
 
 // This class allows us to ensure lineboxes are created in the right place on the line when
 // an out-of-flow positioned object or an empty inline is encountered between a trailing space
 // and subsequent spaces and we want to ignore (i.e. collapse) surplus whitespace. So for example:
 //   <div>X <span></span> Y</div>
 // or
 //   <div>X <div style="position: absolute"></div> Y</div>
 // In both of the above snippets the inline and the positioned object occur after a trailing space
 // and before a space that will cause our line breaking algorithm to start ignoring spaces. When it
 // does that we want to ensure that the inline/positioned object gets a linebox and that it is part
 // of the collapsed whitespace. So to achieve this we use appendObjectIfNeeded() to keep track of
 // objects encountered after a trailing whitespace and updateMidpointsForTrailingObjects() to put
 // them in the right place when we start ignoring surplus whitespace.
 
 class TrailingObjects {
+    STACK_ALLOCATED();
 public:
     TrailingObjects()
         : m_whitespace(nullptr)
     {
     }
 
     void setTrailingWhitespace(LineLayoutText whitespace)
     {
         ASSERT(whitespace);
         m_whitespace = whitespace;
@@ skipping 19 matching lines @@
     void updateMidpointsForTrailingObjects(LineMidpointState&, const InlineIterator& lBreak, CollapseFirstSpaceOrNot);
 
 private:
     LineLayoutText m_whitespace;
     Vector<LineLayoutItem, 4> m_objects;
 };
 
 }
 
 #endif // TrailingObjects_h