[heap] Remove Marking::MarkBlack and some minor cleanups.

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index c2a51e44fbf8fa52f0c4c8c54eb67f1812378afc..3a3c92b1dd5d38ac4c5f87f590a99496641d1f96 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -3062,14 +3062,15 @@ LargePage* LargeObjectSpace::FindPage(Address a) {
 
 
 void LargeObjectSpace::ClearMarkingStateOfLiveObjects() {
-  LargePage* current = first_page_;
-  while (current != NULL) {
-    HeapObject* object = current->GetObject();
-    DCHECK(ObjectMarking::IsBlack(object));
-    ObjectMarking::ClearMarkBit(object);
-    Page::FromAddress(object->address())->ResetProgressBar();
-    Page::FromAddress(object->address())->ResetLiveBytes();
-    current = current->next_page();
+  LargeObjectIterator it(this);
+  for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
+    if (ObjectMarking::IsBlack(obj)) {
+      ObjectMarking::ClearMarkBit(obj);
+      MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
+      chunk->ResetProgressBar();
+      chunk->ResetLiveBytes();
+    }
+    DCHECK(ObjectMarking::IsWhite(obj));
   }
 }