Strengthen a few assertions and add zapping of allocated...

src/heap-inl.h

Index: src/heap-inl.h
===================================================================
--- src/heap-inl.h	(revision 3725)
+++ src/heap-inl.h	(working copy)
@@ -152,7 +152,11 @@
 
 
 bool Heap::InNewSpace(Object* object) {
-  return new_space_.Contains(object);
+  bool result = new_space_.Contains(object);
+  ASSERT(!result ||                  // Either not in new space
+         gc_state_ != NOT_IN_GC ||   // ... or in the middle of GC
+         InToSpace(object));         // ... or in to-space (where we allocate).
+  return result;
 }