Update WebKit to r168231.

BUG=none
TEST=none
TBR=apavlov

Review URL: https://codereview.chromium.org/184193005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254335 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254336 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254336