[test] More debugging output in test runner.
[test] More debugging output in test runner.

Also use again the taskkill method, recently removed in
https://codereview.chromium.org/1156133006/

BUG=chromium:485932
LOG=n
TBR=jkummerow@chromium.org
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/1177903005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#29001}

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