Unify and provide one IsGarbageCollectedType<T> implementation.

third_party/WebKit/Source/platform/heap/HeapAllocator.h

Index: third_party/WebKit/Source/platform/heap/HeapAllocator.h
diff --git a/third_party/WebKit/Source/platform/heap/HeapAllocator.h b/third_party/WebKit/Source/platform/heap/HeapAllocator.h
index 8b43e8b53fa2e0ae2f4c68ca13c53f264aa13b2c..40e0d381d90225e8c4bdae2271e9e72bf48ae07b 100644
--- a/third_party/WebKit/Source/platform/heap/HeapAllocator.h
+++ b/third_party/WebKit/Source/platform/heap/HeapAllocator.h
@@ -23,6 +23,7 @@ namespace blink {
 
 template<typename T, typename Traits = WTF::VectorTraits<T>> class HeapVectorBacking {
     DISALLOW_NEW();
+    IS_GARBAGE_COLLECTED_TYPE();
 public:
     static void finalize(void* pointer);
     void finalizeGarbageCollectedObject() { finalize(this); }
@@ -30,6 +31,7 @@ public:
 
 template<typename Table> class HeapHashTableBacking {
     DISALLOW_NEW();
+    IS_GARBAGE_COLLECTED_TYPE();
 public:
     static void finalize(void* pointer);
     void finalizeGarbageCollectedObject() { finalize(this); }
@@ -544,6 +546,11 @@ struct NeedsTracing<ListHashSetNode<T, blink::HeapListHashSetAllocator<T, inline
     static const bool value = true;
 };
 
+template<typename T, size_t inlineCapacity>
+struct IsGarbageCollectedType<ListHashSetNode<T, blink::HeapListHashSetAllocator<T, inlineCapacity>>> {
+    static const bool value = true;
+};
+
 } // namespace WTF
 
 #endif