Remove __proto__ use from zepto.

This addresses #970 by removing the need to use `__proto__` and instead relying on a technique that more closely resembles jQuery. This also avoids the need for a fallback for IE<11. Tested this with `npm test` as well.
As far as I know, `dom` is always an array-like object, so you don't need to convert it to an array to use as the second argument of `push.apply()`.