Unable to extend custom elements :(

[nimbupani]

Also, the spec is very vague on how templates within custom elements are supposed to work when extended?

I attempted this:

<element name="super-button" extends="button">  
  <template>
      ٩(͡๏̯͡๏)۶ <content></content>
   </template>
</element

and:

<element name="super-super-button" extends="super-button">  
</element>

and using it as:

<button is="super-super-button">hi</button>