Add compat data for -webkit-mask-attachment CSS property (#917)
Add compat data for -webkit-mask-attachment CSS property (#917)

* Add compat data for `-webkit-mask-attachment` CSS property

* Fix -webkit-mask-attachment status to non-experimental

* Fix dubious data for -webkit-mask-attachment

mdn/browser-compat-data,chrisdavidmills/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,teoli2003/browser-compat-data