It concatanates libraries and wraps them into closure defining dependencies.

gulpfile.js

var
    gulp = require('gulp'),
    concat = require('gulp-concat'),
    wrap = require("gulp-wrap");

gulp.task('scripts', function() {
  gulp
    .src([
      './js/modernizr.js',
      './js/webflow.js'
    ])
    .pipe(concat('webflow-pack.js'))
    .pipe(wrap(';(function($) {\n <%= data.contents %> \n})(jq220);', { variable: 'data' }))
    .pipe(gulp.dest('./js'))
});

It make Webflow to work with Drupal.