[BREAKING CHANGE] Unisolate dialogs

We don't really need dialogs to be isolated, because we don't
really need to preserve selections.

Compensate for selection not being preserved by reselecting
the fragment on close in FragmentDialog.

Change-Id: Id425c56d9d246809962b10ecb88010e191c94410
Merge "[BREAKING CHANGE] Unisolate dialogs"