Re-enable test_shell Plugin.* tests for WebKit purify bot.
Re-enable test_shell Plugin.* tests for WebKit purify bot.

TBR=jam
BUG=18598
TEST=WebKit purify bot stays green.

Review URL: http://codereview.chromium.org/164073

git-svn-id: http://src.chromium.org/svn/trunk/src@22634 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 51621d396624e65a59c551be65e30b8296de0273
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser