[heap] Avoid the use of cells to point from code to new-space objects.

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index 859276db34469a14df02e0a4f8b787fba6be365e..988db42a9b8639f33ef2184b1a574c65cf537a34 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -541,6 +541,7 @@ class MarkCompactCollector {
   }
 
   void RecordRelocSlot(Code* host, RelocInfo* rinfo, Object* target);
+  void RecordRelocSlotToNewSpace(Code* host, RelocInfo* rinfo, Object* target);

[ulan, 2016/06/08 14:37:00]

This function doesn't belong to incremental marking and mark compactor because
it is recording slot for scavenger.

Let's move it to Heap new  Heap::RecordWrite and call it 
Heap::RecordWriteToCode.

[ahaas, 2016/06/09 10:34:32]

Done. I had to put the implementation into heap.cc because of the inline header
nightmare.

   void RecordCodeEntrySlot(HeapObject* host, Address slot, Code* target);
   void RecordCodeTargetPatch(Address pc, Code* target);
   INLINE(void RecordSlot(HeapObject* object, Object** slot, Object* target));