Enable assertions and debugging code in the release...

src/heap.cc

Index: src/heap.cc
===================================================================
--- src/heap.cc	(revision 3745)
+++ src/heap.cc	(working copy)
@@ -3940,8 +3940,9 @@
   void VisitPointers(Object** start, Object** end) {
     // Copy all HeapObject pointers in [start, end)
     for (Object** p = start; p < end; p++) {
-      if ((*p)->IsHeapObject())
+      if ((*p)->IsHeapObject()) {
         UnmarkObjectRecursively(p);
+      }
     }
   }
 };