Quick fix for bot failure on "AMDGPU/SIInsertSkips: Fix the determination of...

Quick fix for bot failure on "AMDGPU/SIInsertSkips: Fix the determination of whether early-exit-after-kill is possible"

Apparently the dominator tree update is incorrect, will investigate.

Change-Id: Ie76f8d11b22a552af1f098c893773f3d85e02d4f