Update V8 to version 3.23.15.

R=dslomov@chromium.org
TBR=dslomov@chromium.org

Review URL: https://codereview.chromium.org/96823003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237923 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237924 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237924