Polymer/ShadowDOM — pull request #292 by sigmundch (2013-11-01 21:12:41+00:00)
Title: Preserve 'extends' when the ShadowDOM polyfill patches document.register

I noticed this bug only when using the shadow-dom polyfill in combination with the native document.register. Here is a sample repro example:

```html

```

You'd expect to see: `b created` and `c created`, but only `b created` is called.