The test is flaky because the OS does not sleep for the full requested
time. Adding a check for the OS sleep time.

Bug: v8:7492
Change-Id: I495ecc6595238bc1771adc434e766543513a0256
Reviewed-on: https://chromium-review.googlesource.com/937818Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Fadi Meawad <fmeawad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51774}