Roll DEPS for WebKit 60870:60893.

BUG=none
TEST=none
TBR=hamaji

Review URL: http://codereview.chromium.org/2778004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@49259 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

 vars = {
   "webkit_trunk":
   "http://svn.webkit.org/repository/webkit/trunk",
-  "webkit_revision": "60868",
+  "webkit_revision": "60893",
   "ffmpeg_revision": "49210",
   "skia_revision": "562",
   "chromium_git": "http://src.chromium.org/git",