Refactor the Heap into ThreadHeap to prepare for per thread heaps

third_party/WebKit/Source/core/dom/ElementData.h

Index: third_party/WebKit/Source/core/dom/ElementData.h
diff --git a/third_party/WebKit/Source/core/dom/ElementData.h b/third_party/WebKit/Source/core/dom/ElementData.h
index 63eab9b5b4a5ca1928a2c6d64b9b5f21849cb58a..e939f1ba63c7900dc8807db8dbfb0e61773a35d1 100644
--- a/third_party/WebKit/Source/core/dom/ElementData.h
+++ b/third_party/WebKit/Source/core/dom/ElementData.h
@@ -136,7 +136,7 @@ public:
 
     // Add support for placement new as ShareableElementData is not allocated
     // with a fixed size. Instead the allocated memory size is computed based on
-    // the number of attributes. This requires us to use Heap::allocate directly
+    // the number of attributes. This requires us to use ThreadHeap::allocate directly
     // with the computed size and subsequently call placement new with the
     // allocated memory address.
     void* operator new(std::size_t, void* location)