Add selenium to the Chrome OS test image

Files downloaded from
http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/dev-python/selenium/

BUG=chromium:289701
TEST=TODO: make a trybot build

Change-Id: Id9e220857471def90ec3566a2fde7db4dca4ceff
Reviewed-on: https://chromium-review.googlesource.com/169969
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
4 files changed