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

Source/core/dom/DOMArrayPiece.h

Index: Source/core/dom/DOMArrayPiece.h
diff --git a/Source/core/dom/DOMArrayPiece.h b/Source/core/dom/DOMArrayPiece.h
index 8ca842d6423240ac2673fc4bae760cec9013943c..afa2cb6cdb6b57ed9602efdb9c731ae645919bd2 100644
--- a/Source/core/dom/DOMArrayPiece.h
+++ b/Source/core/dom/DOMArrayPiece.h
@@ -23,6 +23,7 @@ class ArrayBufferOrArrayBufferView;
 // IMPORTANT: The data contained by ArrayPiece is NOT OWNED, so caution must be
 //            taken to ensure it is kept alive.
 class CORE_EXPORT DOMArrayPiece : public WTF::ArrayPiece {
+    DISALLOW_ALLOCATION();
 public:
     enum InitWithUnionOption {
         // Initialize this object as "null" when initialized with an union which