Adding tests for Math.roundFloat32
Adding partial implementation of roundFloat32
Adding in numberConversion methods from https://github.com/inexorabletash/polyfill/blob/master/typedarray.js#L172-L278
Adding TypedArray approach for environments that support typed arrays.
Renaming to Math.fround, per https://github.com/rwaldron/tc39-notes/blob/master/es6/2013-09/sept-17.md