Oilpan: support eager tracing of objects when marking.

Source/platform/heap/Heap.h

Index: Source/platform/heap/Heap.h
diff --git a/Source/platform/heap/Heap.h b/Source/platform/heap/Heap.h
index 791226349747b878b8b0e0560dfdf3c59cda9c88..ee136e71dbef5f492855bea518bd3ed914e61eb0 100644
--- a/Source/platform/heap/Heap.h
+++ b/Source/platform/heap/Heap.h
@@ -97,11 +97,6 @@ const uint8_t finalizedZapValue = 24;
 const uint8_t orphanedZapValue = 240;
 const int numberOfPagesToConsiderForCoalescing = 100;
 
-enum CallbackInvocationMode {
-    GlobalMarking,
-    ThreadLocalMarking,
-};
-
 class CallbackStack;
 class PageMemory;
 template<ThreadAffinity affinity> class ThreadLocalPersistents;
@@ -887,7 +882,7 @@ public:
 
     // Pop the top of a marking stack and call the callback with the visitor
     // and the object. Returns false when there is nothing more to do.
-    template<CallbackInvocationMode Mode> static bool popAndInvokeTraceCallback(CallbackStack*, Visitor*);
+    static bool popAndInvokeTraceCallback(CallbackStack*, Visitor*);
 
     // Remove an item from the post-marking callback stack and call
     // the callback with the visitor and the object pointer. Returns
@@ -914,7 +909,7 @@ public:
     static void collectGarbage(ThreadState::StackState, ThreadState::CauseOfGC = ThreadState::NormalGC);
     static void collectGarbageForTerminatingThread(ThreadState*);
     static void collectAllGarbage();
-    template<CallbackInvocationMode Mode> static void processMarkingStack();
+    static void processMarkingStack();
     static void postMarkingProcessing();
     static void globalWeakProcessing();
     static void setForcePreciseGCForTesting();