Return error not null for date time format.

BUG=v8:1602
TEST=new (new v8Locale().createDateTimeFormat()).getWeekdays should return Error not a Null.
Review URL: http://codereview.chromium.org/7647027

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8935 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/extensions/experimental/datetime-format.cc

@@ -135,7 +135,7 @@ v8::Handle<v8::Value> DateTimeFormat::GetMonths(const v8::Arguments& args) {
 v8::Handle<v8::Value> DateTimeFormat::GetWeekdays(const v8::Arguments& args) {
   icu::SimpleDateFormat* date_format = UnpackDateTimeFormat(args.Holder());
   if (!date_format) {
-    ThrowUnexpectedObjectError();
+    return ThrowUnexpectedObjectError();
   }
 
   const icu::DateFormatSymbols* symbols = date_format->getDateFormatSymbols();