Split polyfill

I modified String.prototype.trim to a smaller version, which is attributed to MDN.

Before my revision we were at:

    Minified: 24.916k
    Minified and gzipped: 9.080k, compression factor 5.599

Now, we're at:

    Minified: 24.897k
    Minified and gzipped: 9.080k, compression factor 5.608

I'm not sure how to remove commit 4c557d1, but it's already been merged.