Revert of Revert of [turbofan] Small fixes to PipelineStatistics. Collect statistics in tests. (patchset #1 id:1 of https://codereview.chromium.org/1119963003/)

Reason for revert:
Revert didn't fix the problem. Maybe it was another CL.

Original issue's description:
> 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=
>
> Committed: https://crrev.com/d0ed8940fc6c995eba57149b8e8cb214001e8381
> Cr-Commit-Position: refs/heads/master@{#28205}

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

Review URL: https://codereview.chromium.org/1126603002

Cr-Commit-Position: refs/heads/master@{#28207}