Oilpan: Introduce WeakProcessingVisitor

Source/platform/heap/InlinedGlobalMarkingVisitor.h

Index: Source/platform/heap/InlinedGlobalMarkingVisitor.h
diff --git a/Source/platform/heap/InlinedGlobalMarkingVisitor.h b/Source/platform/heap/InlinedGlobalMarkingVisitor.h
index 1bc5ac80bafc779bc94e206dc64314ae8d9a1c73..9d895c079f8895b5b1eae5dbb7a1cbb0c98c868a 100644
--- a/Source/platform/heap/InlinedGlobalMarkingVisitor.h
+++ b/Source/platform/heap/InlinedGlobalMarkingVisitor.h
@@ -19,7 +19,7 @@ public:
     explicit InlinedGlobalMarkingVisitor(Visitor* visitor)
         : m_visitor(visitor)
     {
-        ASSERT(visitor->isGlobalMarkingVisitor());
+        ASSERT(visitor->markingMode() == Visitor::GlobalMarking);
     }
 
     // Hack to unify interface to visitor->trace().
@@ -58,6 +58,11 @@ protected:
         return true;
     }
 
+    inline Visitor::MarkingMode markingMode() const
+    {
+        return m_visitor->markingMode();
+    }
+
 #if ENABLE(GC_PROFILING)
     inline void recordObjectGraphEdge(const void* objectPointer)
     {