title: using `filterBy` with dynamic select list
body: <p>I'm building a form with a long list of select items using <code>vue.js</code>. I'm using the dynamic select list documented here: <a href="http://012.vuejs.org/guide/forms.html#Dynamic_Select_Options" rel="nofollow">http://012.vuejs.org/guide/forms.html#Dynamic_Select_Options</a></p>
  
  <p>However, I want to allow users to quickly filter this list using the <a href="http://vuejs.org/api/#filterBy" rel="nofollow"><code>filterBy</code></a> directive. I don't see how you can combine these two-- is it possible to filter a dynamic list? Or can <code>filterBy</code> only be used against a <code>v-for</code>?</p>