Distributed children break focus wrapping

[valdrinkoshi]

Description

Focusable children that are distributed into an overlay by another element break the focus wrapping

<template>
  <p> x-element </p>
  <paper-dialog>
    <content></content>
  </paper-dialog>
</template>
...

<x-element>
  <button> Breaks focus wrapping </button>
</x-element>

Live Demo

http://jsbin.com/tojoroyibi/1/edit?html,output