[test] Fix assert for predictable mode in test runner.
[test] Fix assert for predictable mode in test runner.

NOTRY=true

Review URL: https://codereview.chromium.org/1156663009

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#28679}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh