Fix RollUp-Error because of This is Undefined Rewrite

[Uzlopak]

make it compatible with RollUp
rollup/rollup#759
parallax/jsPDF#1533

[eligrey]

See eligrey/Blob.js#56 (comment)

I don't need this.content || this, so you can just remove it entirely. Once you've made that change I will merge this.

[eligrey]

Actually, just || this is fine, and shouldn't cause any rollup errors. Don't forget to also increment the version number and timestamp at the top to 1.3.4 and 2017-01-12. Then I will merge this.

[eligrey]

Oops, I merged with this.content still. I'll fix that.

[Uzlopak]

Thank you!