title: Vue.js Cannot get correctly some element properties from $refs
body: <p>I cannot get correctly properties from a $refs, feedbacks welcome ...</p>
  
  <p><strong>Vue template</strong></p>
  
  <pre><code>    &lt;input name="title" ref="inputTitle" data-vv-delay="1000" v-validate.initial="'required|min:3'" :class="{'input': true, 'is-danger': errors.has('required') }" :value="title" @input="validating({ title: $event.target.value, id: id })"/&gt;
  </code></pre>
  
  <p><strong>console output</strong></p>
  
  <pre><code>    console.log('REFS: ', this.$refs.inputTitle)
      REFS:
      &lt;input data-v-44a1f54e name="title" data-vv-delay="1000" class="input" data-vv-id="_o6kpv3eo7" aria-required="true" aria-invalid="false"&gt;
  
      console.log('NAME: ', this.$refs.inputTitle.name)
      NAME:  title
  </code></pre>
  
  <p><strong>BUT I get errors with :</strong></p>
  
  <pre><code>    1 - property is not found however it exists...
      console.log('CLASS: ', this.$refs.inputTitle.class)
      CLASS:  undefined
  
      2- aria-invalid is checked as an infix-operator by Lint ...
      console.log('ARIA-INVALID: ', this.$refs.inputTitle.aria-invalid)
      http://eslint.org/docs/rules/space-infix-ops  Infix operators must be spaced
      http://eslint.org/docs/rules/no-undef         'invalid' is not defined
  </code></pre>