Remove unused private member variables found by clang -Wunused-private-field

src/incremental-marking.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 320 matching lines @@
                                             heap_object->Size());
       return true;
     }
     return false;
   }
 };
 
 
 class IncrementalMarkingRootMarkingVisitor : public ObjectVisitor {
  public:
-  IncrementalMarkingRootMarkingVisitor(Heap* heap,
-                                       IncrementalMarking* incremental_marking)
-      : heap_(heap),
-        incremental_marking_(incremental_marking) {
+  explicit IncrementalMarkingRootMarkingVisitor(
+      IncrementalMarking* incremental_marking)
+      : incremental_marking_(incremental_marking) {
   }
 
   void VisitPointer(Object** p) {
     MarkObjectByPointer(p);
   }
 
   void VisitPointers(Object** start, Object** end) {
     for (Object** p = start; p < end; p++) MarkObjectByPointer(p);
   }
 
  private:
   void MarkObjectByPointer(Object** p) {
     Object* obj = *p;
     if (!obj->IsHeapObject()) return;
 
     HeapObject* heap_object = HeapObject::cast(obj);
     MarkBit mark_bit = Marking::MarkBitFrom(heap_object);
     if (mark_bit.data_only()) {
       MarkBlackOrKeepGrey(heap_object, mark_bit, heap_object->Size());
     } else {
       if (Marking::IsWhite(mark_bit)) {
         incremental_marking_->WhiteToGreyAndPush(heap_object, mark_bit);
       }
     }
   }
 
-  Heap* heap_;
   IncrementalMarking* incremental_marking_;
 };
 
 
 void IncrementalMarking::Initialize() {
   IncrementalMarkingMarkingVisitor::Initialize();
 }
 
 
 void IncrementalMarking::SetOldSpacePageFlags(MemoryChunk* chunk,
@@ skipping 239 matching lines @@
   heap_->CompletelyClearInstanceofCache();
   heap_->isolate()->compilation_cache()->MarkCompactPrologue();
 
   if (FLAG_cleanup_code_caches_at_gc) {
     // We will mark cache black with a separate pass
     // when we finish marking.
     MarkObjectGreyDoNotEnqueue(heap_->polymorphic_code_cache());
   }
 
   // Mark strong roots grey.
-  IncrementalMarkingRootMarkingVisitor visitor(heap_, this);
+  IncrementalMarkingRootMarkingVisitor visitor(this);
   heap_->IterateStrongRoots(&visitor, VISIT_ONLY_STRONG);
 
   // Ready to start incremental marking.
   if (FLAG_trace_incremental_marking) {
     PrintF("[IncrementalMarking] Running\n");
   }
 }
 
 
 void IncrementalMarking::PrepareForScavenge() {
@@ skipping 353 matching lines @@
   bytes_scanned_ = 0;
   write_barriers_invoked_since_last_step_ = 0;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSizeOfObjects();
 }
 
 } }  // namespace v8::internal