Fix retainer profile test regression

TBR=sgjesse@chromium.org

Review URL: http://codereview.chromium.org/338014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3126 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap-profiler.cc

@@ -148,7 +148,7 @@ class ReferencesExtractor : public ObjectVisitor {
       inside_array_ = true;
       FixedArray::cast(*o)->Iterate(this);
       inside_array_ = false;
-    } else {
+    } else if ((*o)->IsHeapObject()) {
       profile_->StoreReference(cluster_, HeapObject::cast(*o));
     }
   }