Implement map collection for incremental marking.

src/incremental-marking-inl.h

Index: src/incremental-marking-inl.h
diff --git a/src/incremental-marking-inl.h b/src/incremental-marking-inl.h
index 5ce003f31d4c0d27e81a66df22ad269f11810ca4..2dae6f207d0a3904408c052e791e638d6ebf7f4f 100644
--- a/src/incremental-marking-inl.h
+++ b/src/incremental-marking-inl.h
@@ -1,4 +1,4 @@
-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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:
@@ -118,13 +118,29 @@ void IncrementalMarking::BlackToGreyAndUnshift(HeapObject* obj,
 
 
 void IncrementalMarking::WhiteToGreyAndPush(HeapObject* obj, MarkBit mark_bit) {
-  WhiteToGrey(obj, mark_bit);
+  Marking::WhiteToGrey(mark_bit);
   marking_deque_.PushGrey(obj);
 }
 
 
-void IncrementalMarking::WhiteToGrey(HeapObject* obj, MarkBit mark_bit) {
-  Marking::WhiteToGrey(mark_bit);
+bool IncrementalMarking::MarkObjectAndPush(HeapObject* obj) {
+  MarkBit mark_bit = Marking::MarkBitFrom(obj);
+  if (!mark_bit.Get()) {
+    WhiteToGreyAndPush(obj, mark_bit);
+    return true;
+  }
+  return false;
+}
+
+
+bool IncrementalMarking::MarkObjectWithoutPush(HeapObject* obj) {
+  MarkBit mark_bit = Marking::MarkBitFrom(obj);
+  if (!mark_bit.Get()) {
+    mark_bit.Set();
+    MemoryChunk::IncrementLiveBytesFromGC(obj->address(), obj->Size());
+    return true;
+  }
+  return false;
 }