demo-snippet rendered as inline when useNativeCSSProperties and lazyRegister are enabled

[woutervroege]

Description

I enabled useNativeCSSProperties and lazyRegister and added a demo-snippet to my file. The <div class="demo"></div> is rendered inline instead of block.

As a result, my-element doesn't render correctly inside the demo-snippet

Example code

<script>
      window.Polymer = {
        useNativeCSSProperties: true,
        lazyRegister: true
      };
</script>

<div class="vertical-section-container">
  <h3>Basic my-element Demo</h3>
  <demo-snippet>
    <template>
      <my-element></my-element>
    </template>
  </demo-snippet>
</div>

Browsers Affected

• Chrome 53
• Firefox 46
• Safari 10
  (others untested)