Fix invariant so that we cannot record relocation slots for

src/incremental-marking.h

Index: src/incremental-marking.h
===================================================================
--- src/incremental-marking.h	(revision 12482)
+++ src/incremental-marking.h	(working copy)
@@ -132,6 +132,7 @@
                                                Object** slot,
                                                Isolate* isolate);
 
+  // Returns true if you need to record a slot.

[Vyacheslav Egorov (Google), 2012/09/11 13:51:12]

Enhance comment:

record a slot for compation. Returns false for objects that are guaranteed to be
rescaned or not guaranteed to survive.

No slots in white objects should be recorded as some slots are typed and cannot
be interpreted corrrectly if the underlying object does not survive incremental
cycle (stays white).

   INLINE(bool BaseRecordWrite(HeapObject* obj, Object** slot, Object* value));
   INLINE(void RecordWrite(HeapObject* obj, Object** slot, Object* value));
   INLINE(void RecordWriteIntoCode(HeapObject* obj,