Not resume the invisible TaskFragment when resume top Task

When a TaskFragment is covered by another resumed TaskFragment, this
call would try to resume the activity in the invisible TaskFragment as
well.

However, because the activity would not be visible, so it would also be
called to pause, which would then call to resume the top Task.
It resulted a infinite recurring call of [resume, pause, ...]

Bug: 189385903
Test: manually with splite demo app
Change-Id: I561fec516f0585695e71508c00946355ab0764bb