Mark Page404_GoBack as flaky on linux
Mark Page404_GoBack as flaky on linux

TBR=phajdan.jr
BUG=19361
TEST=ErrorPageTest

Review URL: http://codereview.chromium.org/426011

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@32733 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser