Perf dashboard's should not include results more than 366 days old in JSON

https://bugs.webkit.org/show_bug.cgi?id=151529

Reviewed by Timothy Hatcher.

Don't return results more than 366 days old in /api/runs/ JSON API.
This is a ~5% runtime improvement and reduces the JSON file size by 20-50% in the internal perf dashboard.

* public/api/runs.php:
(main): Added the support for "?noResults" to avoid echoing results. This is useful for debugging.
Also instantiate RunsGenerator before issuing the query to find all configurations so that the runtime cost
of doing so will be included in elapsedTime.
(RunsGenerator::fetch_runs): Skip a row when its build and commit times are more than 366 days old.
(RunsGenerator::format_run): Takes build_time and revisions as arguments since fetch_runs uses them now.
(RunsGenerator::parse_revisions_array): Compute the max of commit times.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@192716 268f45cc-cd09-0410-ab3c-d52691b4dbfc