Compile the file using babel

@param {Object} file the file to process
@param {Object} options the compile options
@return {{content: string, sourceMap: string}}
function compile(file, options) {
    let config = options.config || {};
    let presets = config.presets || [];

    let tsPreset = '@babel/preset-typescript';
    if (!presets.includes(tsPreset)) {
        config.presets = [tsPreset].concat(presets);
        options.config = config;
    }

    return parserHelper.compile(file, options, 7);
}