Updates

- Add Array#find, Array#findIndex
- Array methods follow ToLength spec http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength
- Small updates to DOMTokenList, #toggle polyfill
- Some tests removed from XMLHttpRequest
- Test templates get DOCTYPE

NOTE: I incorrectly merged a commit from "Update XMLHttpRequest tests" into "Update DOMTokenList"
I believe it's due to the bit limit in JavaScript. It's required by the spec here, https://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength

> If len ≤ +0, then return +0.
> Return min(len, 2^53-1).