Drive-by-fix:
- Remove obsolete mark_shared_functions_for_tier_up flag

Bug: chromium:873728
Change-Id: I6c18b2e55068be913a3fc16932a9be0f9f02b635
Reviewed-on: https://chromium-review.googlesource.com/1173232
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55101}