-webkit-transform: translateX(-foo%); for Safari 8

[suzumakes]

Hey, title pretty much says it all, but transform: translateX requires the -webkit prefix to work on Safari 8.

Thanks for your site, it's a useful resource and I'd be happy to help in any way I can.

You're using the default threshold of 0.5% usage globally to filter the needed prefixes aren't you? I'll look into how you're pulling these and at contributing a way to adjust the threshold/switch to current location statistics for you.

[davidhund]

@suzumakes — Thanks Keith, and you're right of course. However, this applies to all transform values, right? ShouldIprefix does mention this for transform so I don't think we should add another entry for one specific value (translateX).

I did notice, however, that I only mention iOS and not iOS < 9.2. That could be an improvement.

As for what prefixes are included:

I have chosen to take a ‘progressive’ approach: when a browser ‘three versions back’ still requires a prefix I will include it. If it is older I exclude that prefix — Disclaimer

So it's a very opinionated and hardly scientific approach ;-)

I have briefly looked at filtering these on a more localized context, but that would require a rewrite: it's simply a jekyll site as of now.

But I'm always happy to take PR's :rocket: