Adding in new Math functions, updating Math.hypot to spec.

# New: 

[**Math.crbt**](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.8.2.32)
[**Math.hypot2**](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.8.2.30)

# Updated:

[**Math.hypot**](http://people.mozilla.org/~jorendorff/es6-draft.html#sec-15.8.2.29)