Backed out 4 changesets (bug 826148) because of test failures

Backed out changeset e520c411aed6 (bug 826148)
Backed out changeset 1db5b4e59649 (bug 826148)
Backed out changeset 57bf735f3e18 (bug 826148)
Backed out changeset b659dc17b164 (bug 826148)
Bug 829180 - Never open externally opened links in a private window; r=gavin