Add Date.toUTCString

global.go

@@ -298,6 +298,7 @@ func newContext() *_runtime {
 		builtinNewDate,
 		self.Global.DatePrototype,
 		"toString", 0, builtinDate_toString,
+		"toUTCString", 0, builtinDate_toUTCString,
 		"valueOf", 0, func(call FunctionCall) Value {
 			date := dateObjectOf(call.thisObject())
 			if date.isNaN {