function isServerHtmlFileExt(filePath) {
        if (!filePath) {
            return false;
        }

        return (_serverHtmlFileExts.indexOf(LanguageManager.getLanguageForPath(filePath).getId()) !== -1);
    }
Determine if file extension is a server html file extension.
@param {string} filePath could be a path, a file name or just a file extension
@return {boolean} Returns true if fileExt is in the list