Perf dashboard should show the results of A/B testing

Perf dashboard should show the results of A/B testing
https://bugs.webkit.org/show_bug.cgi?id=141500

Reviewed by Chris Dumez.

Added the support for fetching test_runs for a specific test group in /api/runs/, and used it in the
analysis task page to fetch results for each test group.

Merged App.createChartData into App.Manifest.fetchRunsWithPlatformAndMetric so that App.BuildRequest
can use the formatter.

* public/api/runs.php:
(fetch_runs_for_config_and_test_group): Added.
(fetch_runs_for_config): Just return the fetched rows since main will format them with RunsGenerator.
(main): Use fetch_runs_for_config_and_test_group to fetch rows when a test group id is specified. Also
use RunsGenerator to format results.
(RunsGenerator): Added.
(RunsGenerator::__construct): Added.
(RunsGenerator::add_runs): Added.
(RunsGenerator::format_run): Moved.
(RunsGenerator::parse_revisions_array): Moved.

* public/v2/analysis.js:
(App.TestGroup): Fixed a typo. The property on a test group that refers to an analysis task is "task".
(App.TestGroup._fetchChartData): Added. Fetches all A/B testing results for this group.
(App.BuildRequest.configLetter): Renamed from config since this returns a letter that identifies the
configuration associated with this build request such as "A" and "B".
(App.BuildRequest.statusLabel): Added the missing label for failed build requests.
(App.BuildRequest.url): Added. Returns the URL associated with this build request.
(App.BuildRequest._meanFetched): Added. Retrieve the mean and the build number for this request via
_fetchChartData.

* public/v2/app.js:
(App.Pane._fetch): Set chartData directly here.
(App.Pane._updateMovingAverageAndEnvelope): Renamed from _computeChartData. No longer sets chartData
now that it's done in App.Pane._fetch.
(App.AnalysisTaskController._fetchedRuns): Updated per createChartData merge.

* public/v2/data.js:
(Measurement.prototype.buildId): Added.
(TimeSeries.prototype.findPointByBuild): Added.

* public/v2/index.html: Fixed a bug that build status URL was broken. We can't use link-to helper since
url is not an Ember routed path.

* public/v2/manifest.js:
(App.Manifest.fetchRunsWithPlatformAndMetric): Takes testGroupId as the third argument. Merged
App.createChartData here so that App.BuildRequest can use the formatter

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@180000 268f45cc-cd09-0410-ab3c-d52691b4dbfc