Fix for IME exclusions not working with expanded bubble

- Technically the IME window is above the Bubble window, but when
  traversing the windows top-down for calculating the final exclusion
  region for SysUI, the IME is placed just above its target (the
  embedded task), and the Bubble's full touchable region effectively
  overrides the IME's requested exclusion region

Fixes: 190338512
Test: Expand a bubble, swipe from IME edge
Change-Id: Idd71eabfaba1be4bc6fc90d09db28d3f9e9106c5