Bug 1100954 - Activities menu has no text after forwarding a SMS. r=julien

:) I believe it's only possible to reproduce in integration test, because the issue is that l10n lib tries to set textContent to the element with nested node inside, fails and doesn't localize anything else, ut in tests we use MockL10n lib that doesn't complain :)

I can add marionettejs test if you're ok with it?