title: Svelte bundle.js is large, full of @license comments, even in production mode
body: <p><code>&gt;npm run build</code> on a modest sized Svelte project produces a large public/build/bundle.js file.  The Javascript code is minimized into a series of one-liners</p>
  
  <p><code>function(t){return new qr((function(e){...</code></p>
  
  <p>but in between (or sometimes in the middle of) every line is a large comment block for licenses</p>
  
  <pre><code> * @license
   * Copyright 2018 Google Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   ... 9 more lines
   * limitations under the License.
  </code></pre>
  
  <p>The date varies, 2017-2019.  There are also a few Microsoft Licenses.  There are roughly 70 of these licenses sprinkled in the code, making it bloat up to 800kb.</p>
  
  <p>I haven't messed with rollup config or anything.
  Here's package.json relevant sections:</p>
  
  <pre><code>"scripts": {
      "build": "rollup -c",
      "dev": "rollup -c -w",
      "start": "sirv public"
    },
    "devDependencies": {
      "@rollup/plugin-commonjs": "^11.0.0",
      "@rollup/plugin-node-resolve": "^7.0.0",
      "rollup": "^1.20.0",
      "rollup-plugin-livereload": "^1.0.0",
      "rollup-plugin-svelte": "^5.0.3",
      "rollup-plugin-terser": "^5.1.2",
      "svelte": "^3.0.0",
      "svelte-mui": "^0.3.3"
    },
  </code></pre>
  
  <p>I've tried deleting node_modules and redoing <code>npm install</code> to no effect.  I"m running on Windows 10 if that matters.</p>