Oilpan: Add TraceEargerlyTrait for WeakPersistent and CrossThreadWeakPersistent

Just for consistency. This won't affect practical performance.

BUG=

Review URL: https://codereview.chromium.org/1317033008

git-svn-id: svn://svn.chromium.org/blink/trunk@201786 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -23,11 +23,13 @@
 namespace blink {
 
 template<typename T> class CrossThreadPersistent;
+template<typename T> class CrossThreadWeakPersistent;
 template<typename T> struct GCInfoTrait;
 class HeapObjectHeader;
 template<typename T> class Member;
 template<typename T> class TraceTrait;
 template<typename T> class WeakMember;
+template<typename T> class WeakPersistent;
 
 template<typename T, bool = NeedsAdjustAndMark<T>::value> class AdjustAndMarkTrait;
 
@@ -285,12 +287,24 @@ public:
     static const bool value = TraceEagerlyTrait<T>::value;
 };
 
+template<typename T>
+class TraceEagerlyTrait<WeakPersistent<T>> {
+public:
+    static const bool value = TraceEagerlyTrait<T>::value;
+};
+
 template<typename T>
 class TraceEagerlyTrait<CrossThreadPersistent<T>> {
 public:
     static const bool value = TraceEagerlyTrait<T>::value;
 };
 
+template<typename T>
+class TraceEagerlyTrait<CrossThreadWeakPersistent<T>> {
+public:
+    static const bool value = TraceEagerlyTrait<T>::value;
+};
+
 template<typename ValueArg, size_t inlineCapacity> class HeapListHashSetAllocator;
 template<typename T, size_t inlineCapacity>
 class TraceEagerlyTrait<WTF::ListHashSetNode<T, HeapListHashSetAllocator<T, inlineCapacity>>> {