Since revision r176978 <http://trac.webkit.org/r176978> the layout test fast/regions/overflow/overflow-region-inline.html fails on platform GTK: Regressions: Unexpected image-only failures (1) fast/regions/overflow/overflow-region-inline.html [ ImageOnlyFailure ] The diff is: https://build.webkit.org/results/GTK%20Linux%2064-bit%20Release%20%28Tests%29/r176981%20%284708%29/fast/regions/overflow/overflow-region-inline-diffs.html
CSS Regions were removed in Bug 174978.