The test does not take into account that Turbofan can force completion
of in-object slack tracking.

Bug: 
Change-Id: Ic7404e8395858acaf707e65ca4b17e6b7f776594
Reviewed-on: https://chromium-review.googlesource.com/723464Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48687}