Cheaper thread-safe atomic initialization of static references.

Source/core/dom/DOMArrayBuffer.h

Index: Source/core/dom/DOMArrayBuffer.h
diff --git a/Source/core/dom/DOMArrayBuffer.h b/Source/core/dom/DOMArrayBuffer.h
index ab3e4af942a0ef3471cf0c272a40264c0b3d3dea..d959b337e09d9e25496affa064b35a21942616a8 100644
--- a/Source/core/dom/DOMArrayBuffer.h
+++ b/Source/core/dom/DOMArrayBuffer.h
@@ -55,7 +55,7 @@ public:
     }
     bool transfer(WTF::ArrayBufferContents& result) { return buffer()->transfer(result); }
     bool isNeutered() { return buffer()->isNeutered(); }
-    void setDeallocationObserver(DOMArrayBufferDeallocationObserver* observer)
+    void setDeallocationObserver(DOMArrayBufferDeallocationObserver& observer)
     {
         buffer()->setDeallocationObserver(observer);
     }