Oilpan: Remove a visitor parameter from isHeapObjectAlive

Source/platform/heap/MarkingVisitor.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MarkingVisitor_h
 #define MarkingVisitor_h
 
 #include "platform/heap/MarkingVisitorImpl.h"
 
 namespace blink {
@@ skipping 40 matching lines @@
         Impl::registerWeakTable(closure, iterationCallback, iterationDoneCallback);
     }
 
 #if ENABLE(ASSERT)
     virtual bool weakTableRegistered(const void* closure)
     {
         return Impl::weakTableRegistered(closure);
     }
 #endif
 
-    virtual bool isMarked(const void* objectPointer) override
-    {
-        return Impl::isMarked(objectPointer);
-    }
-
     virtual bool ensureMarked(const void* objectPointer) override
     {
         return Impl::ensureMarked(objectPointer);
     }
 
 #if ENABLE(GC_PROFILING)
     virtual void recordObjectGraphEdge(const void* objectPointer) override
     {
         MutexLocker locker(objectGraphMutex());
         String className(classOf(objectPointer));
@@ skipping 124 matching lines @@
     virtual void checkMarkingAllowed() override
     {
         ASSERT(ThreadState::current()->isInGC());
     }
 #endif
 };
 
 } // namespace blink
 
 #endif