Remove unnecessary MemberHash<> templates.

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

Index: third_party/WebKit/Source/platform/heap/Persistent.h
diff --git a/third_party/WebKit/Source/platform/heap/Persistent.h b/third_party/WebKit/Source/platform/heap/Persistent.h
index 4bee328aa34193b31aff00a2a46dd51b657479ac..1ad18d1e3e628f1e2cc629298ff3ae7d38ca56fc 100644
--- a/third_party/WebKit/Source/platform/heap/Persistent.h
+++ b/third_party/WebKit/Source/platform/heap/Persistent.h
@@ -693,25 +693,27 @@ template<typename T, typename U> inline bool operator!=(const Persistent<T>& a,
 namespace WTF {
 
 template <typename T>
-struct PersistentHash : MemberHash<T> {
-    STATIC_ONLY(PersistentHash);
+struct DefaultHash<blink::Persistent<T>> {
+    STATIC_ONLY(DefaultHash);
+    using Hash = MemberHash<T>;
 };
 
 template <typename T>
-struct CrossThreadPersistentHash : MemberHash<T> {
-    STATIC_ONLY(CrossThreadPersistentHash);
+struct DefaultHash<blink::WeakPersistent<T>> {
+    STATIC_ONLY(DefaultHash);
+    using Hash = MemberHash<T>;
 };
 
 template <typename T>
-struct DefaultHash<blink::Persistent<T>> {
+struct DefaultHash<blink::CrossThreadPersistent<T>> {
     STATIC_ONLY(DefaultHash);
-    using Hash = PersistentHash<T>;
+    using Hash = MemberHash<T>;
 };
 
 template <typename T>
-struct DefaultHash<blink::CrossThreadPersistent<T>> {
+struct DefaultHash<blink::CrossThreadWeakPersistent<T>> {
     STATIC_ONLY(DefaultHash);
-    using Hash = CrossThreadPersistentHash<T>;
+    using Hash = MemberHash<T>;
 };
 
 template<typename T>