Use proper gtest macros for testing expected values.

R=leszeks@chromium.org

Bug: v8:10426
Change-Id: Ibdbbf4d05b0a8914f52a270d21a9087c019396b0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2152836Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67206}