{{yield this}}
{{#ember-wormhole to="paper-wormhole"}}
  {{paper-backdrop  tap="toggleMenu"}}
{{/ember-wormhole}}
{{yield this}}
{{#ember-wormhole to="paper-wormhole"}}
  {{paper-backdrop class="md-select-backdrop" tap="toggleMenu"}}
{{/ember-wormhole}}

Add class to select backdrop
Add class to select backdrop