Linux test_shell: always use hermetic fontconfig mode.
Linux test_shell: always use hermetic fontconfig mode.

This is just a temporary change to debug a layout test failure which
I cannot replicate anywhere.

git-svn-id: http://src.chromium.org/svn/trunk/src@42117 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: faf5894116634c71d35fa92c2b0285d9847efa71
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