Fix debug builds.

src/heap-inl.h

Index: src/heap-inl.h
===================================================================
--- src/heap-inl.h	(revision 1972)
+++ src/heap-inl.h	(working copy)
@@ -191,6 +191,27 @@
 }
 
 
+void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
+  ASSERT(InFromSpace(object));
+
+  // We use the first word (where the map pointer usually is) of a heap
+  // object to record the forwarding pointer.  A forwarding pointer can
+  // point to an old space, the code space, or the to space of the new
+  // generation.
+  MapWord first_word = object->map_word();
+
+  // If the first word is a forwarding address, the object has already been
+  // copied.
+  if (first_word.IsForwardingAddress()) {
+    *p = first_word.ToForwardingAddress();
+    return;
+  }
+
+  // Call the slow part of scavenge object.
+  return ScavengeObjectSlow(p, object);
+}
+
+
 Object* Heap::GetKeyedLookupCache() {
   if (keyed_lookup_cache()->IsUndefined()) {
     Object* obj = LookupCache::Allocate(4);