internal static extern JavaScriptErrorCode JsCreateExternalObject( IntPtr data, JavaScriptGenericCallback finalizeCallback, out JavaScriptValue obj);
internal static extern JavaScriptErrorCode JsSetObjectBeforeCollectCallback( JavaScriptValue reference, IntPtr callbackState, JavaScriptGenericCallback beforeCollectCallback);
internal static extern JavaScriptErrorCode JsSetRuntimeBeforeCollectCallback( JavaScriptRuntime runtime, IntPtr callbackState, JavaScriptGenericCallback beforeCollectCallback);