`registerElement` should support callbacks coming from deep prototype chains

The following line:

https://github.com/angular/zone.js/blob/26a4dc27f781afb6e6dd1258a15cb8c0840c706d/zone.js#L663

Checks `if (opts.prototype[callback])` and then uses `Object.getOwnPropertyDescriptor(opts.prototype, callback)` to retrieve it. If the callback comes from the prototype chain we cannot use `getOwnPropertyDescriptor`.
