Mark SessionHistoryTest.JavascriptHistory as flaky.
Mark SessionHistoryTest.JavascriptHistory as flaky.

BUG=50648
TEST=none
Review URL: http://codereview.chromium.org/3073009

git-svn-id: http://src.chromium.org/svn/trunk/src@54139 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 5ae2379c7543132aa7d693d706d5b7fc2ff634ee
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