Cheaper thread-safe atomic initialization of static references.

Source/wtf/ArrayBufferContents.h

Index: Source/wtf/ArrayBufferContents.h
diff --git a/Source/wtf/ArrayBufferContents.h b/Source/wtf/ArrayBufferContents.h
index 5f227ed8ddafe59028b0fca629654abd74b6c365..4bd137f02ce984f0fe9c70f30e1564b269498f7a 100644
--- a/Source/wtf/ArrayBufferContents.h
+++ b/Source/wtf/ArrayBufferContents.h
@@ -58,17 +58,17 @@ public:
     void* data() const { return m_data; }
     unsigned sizeInBytes() const { return m_sizeInBytes; }
 
-    void setDeallocationObserver(ArrayBufferDeallocationObserver* observer)
+    void setDeallocationObserver(ArrayBufferDeallocationObserver& observer)
     {
         if (!m_deallocationObserver) {
-            m_deallocationObserver = observer;
+            m_deallocationObserver = &observer;
             m_deallocationObserver->blinkAllocatedMemory(m_sizeInBytes);
         }
     }
-    void setDeallocationObserverWithoutAllocationNotification(ArrayBufferDeallocationObserver* observer)
+    void setDeallocationObserverWithoutAllocationNotification(ArrayBufferDeallocationObserver& observer)
     {
         if (!m_deallocationObserver) {
-            m_deallocationObserver = observer;
+            m_deallocationObserver = &observer;
         }
     }