code: function compilejs(sources, outdir, outfile, opt_options) {
    var bundler = browserify({
      entries: sources,
      debug: false
    });
    return rebundle_(bundler, outdir, outfile, opt_options);
  }
docs: Compiles js code using browserify and uglify.
  @param {Array.<string>} sources List of JS source files.
  @param {string} outdir Output directory.
  @param {string} outfile Output file name.
  @param {Object=} opt_options Options.