Remove -o-box-sizing from .box-sizing LESS mixin

I doubt it even exists. MDN and caniuse.com don't mention it:
https://developer.mozilla.org/en-US/docs/Web/CSS/box-sizing
http://caniuse.com/css3-boxsizing

Change-Id: I04fe604d380d8d7fbc7dc83fc80be4046989bc71
Merge "Remove -o-box-sizing from .box-sizing LESS mixin"