Make classes and structures in core/style, core/plugins and core/streams fast-allocated.

Source/core/style/StyleDifference.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 StyleDifference_h
 #define StyleDifference_h
 
+#include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 class StyleDifference {
+    STACK_ALLOCATED();
 public:
     enum PropertyDifference {
         TransformChanged = 1 << 0,
         OpacityChanged = 1 << 1,
         ZIndexChanged = 1 << 2,
         FilterChanged = 1 << 3,
         BackdropFilterChanged = 1 << 4,
         // The object needs to issue paint invalidations if it contains text or properties dependent on color (e.g., border or outline).
         TextOrColorChanged = 1 << 5,
         // If you add a value here, be sure to update the number of bits on m_propertySpecificDifferences.
@@ skipping 73 matching lines @@
         FullLayout
     };
     unsigned m_layoutType : 2;
 
     unsigned m_propertySpecificDifferences : 6;
 };
 
 } // namespace blink
 
 #endif // StyleDifference_h