[heap] Give marking functions for incremental marking more precise names.

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index acbddbbaa102c012e5e46c04c550993e07bffb5a..877f05e0e01540f4c7744ae8ab2b6bd60da3415b 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -204,7 +204,9 @@ class IncrementalMarking {
 
   bool IsIdleMarkingDelayCounterLimitReached();
 
-  static void MarkObject(Heap* heap, HeapObject* object);
+  static void MarkGrey(Heap* heap, HeapObject* object);
+
+  static void MarkBlack(HeapObject* object, int size);
 
   static void TransferMark(Heap* heap, Address old_start, Address new_start);