I wrote a test for -webkit-mask and found a problem with the handling of <box>{1,2} values (-webkit-mask-clip and -webkit-mask-origin). What ever you do, the values always get switched. This is not the case for background: PASS innerStyle("background", "none padding-box content-box") is "none padding-box content-box" PASS innerStyle("background", "none content-box padding-box") is "none content-box padding-box" FAIL innerStyle("-webkit-mask", "none padding-box content-box") should be none padding-box content-box. Was none content-box padding-box. FAIL innerStyle("-webkit-mask", "none content-box padding-box") should be none content-box padding-box. Was none padding-box content-box. Same happens in all combination of <box>: border-box, padding-box and content-box.
Looks like the problem is in const StylePropertyShorthand& webkitMaskShorthand(), where both properties are in the wrong order.
Created attachment 175704 [details] Patch
Comment on attachment 175704 [details] Patch Clearing flags on attachment: 175704 Committed r135556: <http://trac.webkit.org/changeset/135556>
All reviewed patches have been landed. Closing bug.