Revert of [turbofan] Small fixes to PipelineStatistics. Collect statistics in tests...

Revert of [turbofan] Small fixes to PipelineStatistics. Collect statistics in tests. (patchset #1 id:1 of https://codereview.chromium.org/1122753002/)

Reason for revert:
[Sheriff] Speculative revert for breaking arm64 nosnap:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20nosnap%20-%20debug%20-%202/builds/2314

Original issue's description:
> [turbofan] Small fixes to PipelineStatistics. Collect statistics in tests.
>
> R=bmeurer@chromium.org
> BUG=
>
> Committed: https://crrev.com/9833844268357590243732a53e2a7fc0dc5fcc9e
> Cr-Commit-Position: refs/heads/master@{#28192}

TBR=bmeurer@chromium.org,titzer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1119963003

Cr-Commit-Position: refs/heads/master@{#28205}