Properly track fragments from pop operations.

Bug 33849992

When popping and executing another transaction, the pop
transaction weren't properly tracking the fragments that were
added and removed.

This CL adds tracking the fragments during the pop execution.
It also fixes a small issue in when fragment state was executed
during pop.

Test: I89ed2386220deb21b417cd6674292c12accab18b
Change-Id: Ie693eef38b0136bf8ea76027dbc756b35ee9a366