Detect browser support

[Sergio Behrends]

While testing the library I found that it does not work on Safari 10.0.3.
Is there any way to detect the support of the browser before running the test?

File API is available on Safari, buy maybe there is other dependency.
http://caniuse.com/#feat=fileapi

[James Cryer]

Thanks for raising this, I'm not aware of a reason why it wouldn't work in Safari, I'll label as bug.

I won't look into this myself but am happy to review a Pull Request.

[Giorgio Mennitto]

This issue is still present and it's due to the value of the "crossorigin" value you are setting: if you remove, it it works fine.
I think you don't have to set it if it is not a cross-origin request.