Unbreak NaCL build

TBR=verwaest@chromium.org

Review URL: https://codereview.chromium.org/422863004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22644 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -6636,7 +6636,12 @@ MaybeHandle<Object> JSObject::DefineAccessor(Handle<JSObject> object,
   if (is_observed) {
     if (is_element) {
       Maybe<bool> maybe = HasOwnElement(object, index);
-      ASSERT(maybe.has_value);
+      // Workaround for a GCC 4.4.3 bug which leads to "‘preexists’ may be used
+      // uninitialized in this function".
+      if (!maybe.has_value) {
+        ASSERT(false);
+        return isolate->factory()->undefined_value();
+      }
       preexists = maybe.value;
       if (preexists && GetOwnElementAccessorPair(object, index).is_null()) {
         old_value =