roll skia to 2579

Review URL: http://codereview.chromium.org/8351039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@108123 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -30,7 +30,7 @@ vars = {
   "libvpx_revision": "107145",
   "ffmpeg_revision": "107500",
   "sfntly_revision": "98",
-  "skia_revision": "2576",
+  "skia_revision": "2579",
   "v8_revision": "9637",
   "webrtc_revision": "808",
   "jsoncpp_revision": "246",