Add undefined check for default Array map in ArrayCodeGenericCommon

TBR=jkummerow@chromium.org
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9290064

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10524 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/builtins.cc

@@ -198,8 +198,9 @@ static MaybeObject* ArrayCodeGenericCommon(Arguments* args,
     array->set_length(Smi::FromInt(0));
     array->set_elements(heap->empty_fixed_array());
     if (!FLAG_smi_only_arrays) {
-      if (array->GetElementsKind() == FAST_SMI_ONLY_ELEMENTS) {
-        Context* global_context = isolate->context()->global_context();
+      Context* global_context = isolate->context()->global_context();
+      if (array->GetElementsKind() == FAST_SMI_ONLY_ELEMENTS &&
+          !global_context->object_js_array_map()->IsUndefined()) {
         array->set_map(Map::cast(global_context->object_js_array_map()));
       }
     }