Changing the current file causes issues with gcov.

Bug: v8:8517
Change-Id: Ic9959c64c36a027d205f9bb5aafcee08c84be15f
Reviewed-on: https://chromium-review.googlesource.com/c/1353899Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57908}