The following layout test is failing on GTK. fast/sub-pixel/sub-pixel-composited-layers.html This new test added in r154009 <http://trac.webkit.org/changeset/154009> has been failing from the beginning. http://build.webkit.org/results/GTK%20Linux%2064-bit%20Release/r154098%20%2839846%29/fast/sub-pixel/sub-pixel-composited-layers-diffs.html
This seems to be passing now. Unskipped in r191101