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

Source/core/editing/iterators/FullyClippedStateStack.h

 // Copyright 2015 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 FullyClippedStateStack_h
 #define FullyClippedStateStack_h
 
 #include "core/editing/EditingStrategy.h"
 #include "core/editing/iterators/BitStack.h"
+#include "wtf/Allocator.h"
 
 namespace blink {
 
 template<typename Strategy>
-class FullyClippedStateStackAlgorithm : public BitStack {
+class FullyClippedStateStackAlgorithm final : public BitStack {
+    STACK_ALLOCATED();
 public:
     FullyClippedStateStackAlgorithm();
     ~FullyClippedStateStackAlgorithm();
 
     void pushFullyClippedState(Node*);
     void setUpFullyClippedStack(Node*);
 };
 
 extern template class FullyClippedStateStackAlgorithm<EditingStrategy>;
 extern template class FullyClippedStateStackAlgorithm<EditingInComposedTreeStrategy>;
 
 using FullyClippedStateStack = FullyClippedStateStackAlgorithm<EditingStrategy>;
 
 } // namespace blink
 
 #endif // FullyClippedStateStack_h