[Gecko Bug 1343980] [css-ui] Skip anonymous boxes (rather than all pseudos) when looking for the 'overflow' style frame. r=bz#105

jgraham wants to merge 10 commits into

masterjgraham/web-platform-tests:masterfrom

sync/upstream/open/1343980jgraham/web-platform-tests:sync/upstream/open/1343980Copy head branch name to clipboard