This update for gn, re2 fixes the following issues:

chromium dependencies were updated:

gn was updated to 0.1726:

re2 was updated to version 2020-04-01:

* Update Unicode data to 13.0.0
* Include the pattern length in "DFA out of memory" errorrs

This update was imported from the openSUSE:Leap:15.1:Update update project.