Revert "Fix exit transition and dismiss callback for popup exit transition"

This reverts most of commit 21d361806c9e2dce5bae5b30f44be5ad87f32c22, which
broke too many expectations in both apps and framework widgets. We need to
find a safer way to handle the exit transition callback.

Bug: 27359366
Bug: 27353218
Change-Id: I769ac7a25cb900c50e857839ca0563fbc5a3cb16
1 file changed