Europe/Saratov is a new timezone spun off from Europe/Volgograd.
It switched from +03 to +04 on 2016-12-04 at 02:00.

For more details, see

http://mm.icann.org/pipermail/tz-announce/2016-November/000044.html

BUG=473288
TEST=Try the following in d8 or Chrome's JS console:
> (new Date("12/04/2016 12:00Z")).toLocaleString("en", {timeZone:
"Europe/Saratov"})
"12/4/2016, 4:00:00 PM"
> (new Date("12/03/2016 12:00Z")).toLocaleString("en", {timeZone:
"Europe/Saratov"})
"12/3/2016, 3:00:00 PM"
TBR=mark

Review URL: https://codereview.chromium.org/2558183003 .