Fix Gmail undo state.

We forced all notifications to have an expanded
state, but the Gmail undo notification is totally
broken in that case.  This check exempts an obviosuly
bad expanded state from having to exist, fixing
Gmail's undo flow in the process.

Fixes: 173774694
Bug: 163626038
Bug: 173550917
Test: manual
Change-Id: I8973907ceb06ccf06c0a685fc0f2a2d283794fe5