Cheaper thread-safe atomic initialization of static references.

Source/platform/heap/Heap.cpp

Index: Source/platform/heap/Heap.cpp
diff --git a/Source/platform/heap/Heap.cpp b/Source/platform/heap/Heap.cpp
index 5f2e53e88668a89d9296a576a08ae82f6d1dea23..04be9da29d692c6ca97b7d9c0da13a6c86ca9d54 100644
--- a/Source/platform/heap/Heap.cpp
+++ b/Source/platform/heap/Heap.cpp
@@ -1991,7 +1991,7 @@ public:
 
     static Mutex& objectGraphMutex()
     {
-        AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
+        AtomicallyInitializedStaticReference(Mutex, mutex, new Mutex);
         return mutex;
     }
 
@@ -2626,7 +2626,7 @@ BaseHeapPage* Heap::lookup(Address address)
 
 static Mutex& regionTreeMutex()
 {
-    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
+    AtomicallyInitializedStaticReference(Mutex, mutex, new Mutex);
     return mutex;
 }