Check that ime visibility changes in stack view

This fixes a minor animation issue when expanding the stack while
the IME is visible.

Flag: EXEMPT bug fix
Bug: 379474417
Test: manual
       - have a floating bubble
       - launch app
       - request IME in the app
       - tap on bubble to expand
       - observe expand animation is smooth
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:9f5d9fc65702ab81f7489911857dc52d14c4f1c2)
Merged-In: I2fd4031004f482af94162ffa0188b527ba874813
Change-Id: I2fd4031004f482af94162ffa0188b527ba874813