问MVC4包缩小不适用于javascript保留字

EN

public class CustomBundle : ScriptBundle
{
    public CustomBundle(string virtualPath) : base(virtualPath)
    {
        this.Builder = new CustomBuilder();
    }
    public CustomBundle(string virtualPath, string cdnPath) : base(virtualPath, cdnPath) {}
}

public class CustomBuilder : IBundleBuilder {
    public string BuildBundleContent(Bundle bundle, BundleContext context, IEnumerable<FileInfo> files)
    {
        var content = new StringBuilder();
        foreach (var fileInfo in files)
        {
            var parser = new Microsoft.Ajax.Utilities.JSParser(Read(fileInfo));
            parser.Settings.AddRenamePair("delete", "fooDelete");
            content.Append(parser.Parse(parser.Settings).ToCode());
            content.Append(";");
        }

        return content.ToString();
    }

    private string Read(FileInfo file)
    {
        using(var r = file.OpenText())
        {
            return r.ReadToEnd();
        }
    }
}

var bundle = new ScriptBundle("~/bundles/xxxbundle", null, new JsMinifyIgnoreReservedWordError()).
    Include("~/Scripts/xxx.js");

private class JsMinifyIgnoreReservedWordError : IBundleTransform
{
    private const string JsContentType = "text/javascript";

    public void Process(BundleContext context, BundleResponse response)
    {
        if (context == null)
        {
            throw new ArgumentNullException("context");
        }
        if (response == null)
        {
            throw new ArgumentNullException("response");
        }
        if (!context.EnableInstrumentation)
        {
            Minifier minifier = new Minifier();

            string result = minifier.MinifyJavaScript(response.Content, new CodeSettings
            {
                EvalTreatment = EvalTreatment.MakeImmediateSafe,
                PreserveImportantComments = false,
                        IgnoreErrorList = "JS1137" // ignore 'is a new reserved word and should not be used as an identifier' error
                    });

            if (minifier.ErrorList.Count > 0)
            {
                GenerateErrorResponse(response, minifier.ErrorList);
            }
            else
            {
                response.Content = result;
            }
        }
        response.ContentType = JsContentType;
    }

    private static void GenerateErrorResponse(BundleResponse bundle, IEnumerable<object> errors)
    {
        StringBuilder stringBuilder = new StringBuilder();

        stringBuilder.Append("/* ");
        stringBuilder.Append("Minification failed. Returning unminified contents.").AppendLine();

        foreach (object error in errors)
        {
            stringBuilder.Append(error).AppendLine();
        }

        stringBuilder.Append(" */").AppendLine();
        stringBuilder.Append(bundle.Content);

        bundle.Content = stringBuilder.ToString();
    }
}