Add more output to flaky debug-references test.
Add more output to flaky debug-references test.

R=vogelheim@chromium.org

Review URL: https://codereview.chromium.org/1006873002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#27181}

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