Bug 960017 - Add some debug-only checks. r=Bas

--HG--
extra : rebase_source : 7618902f2cb1d21e402e6fee251c967af518aaf1
Bug 960017 - Make the surfaces big enough. r=Bas

--HG--
extra : rebase_source : fc7cafcc7f39bd1f05478230292816d874a7b035
Bug 941325 - Fix focus ring drawing when building with the 10.8 SDK or higher. r=smichaud

--HG--
extra : rebase_source : 07fa26673188c4d5fb5450ec2344a794e4d67aad
Bug 966996 - Clamp the gradient extents to the current clip extents so that we don't compute unseen gradient stops. r=jrmuizel

--HG--
extra : rebase_source : 5ccf62603305ff2d88c98512e795fed87badc2c8
Bug 966996 - The computed gradient stops need not cover the origin, so don't start at zero. r=jrmuizel

--HG--
extra : rebase_source : cc8afae8083129aee8765855037fc89ea1280b1c