[chromedriver] Release v2.4.

R=chrisgao@chromium.org, frankf@chromium.org

Review URL: https://codereview.chromium.org/25369002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226067 0039d316-1c4b-4281-b951-d872f2087c98
Remove unnecessary static variable that entangles TEST_F state.

BUG=none

Review URL: https://codereview.chromium.org/24642004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226068 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226068