New flakiness dashboard should support showing the failing tests per builder

New flakiness dashboard should support showing the failing tests per builder
https://bugs.webkit.org/show_bug.cgi?id=123011

Reviewed by Timothy Hatcher.

Added the feature. Also did some refactoring to add this feature.

* ChangeLog: Added.
* api/failing-tests.php: Added.
* api/manifest.php: Removed the code to make maps by id. The work is now done in index.html.
* api/results.php:
* common.css: Added. Extracted from index.html.
* include/test-results.php: Extracted parse_revisions_array and format_result_rows from results.php.
* index.html:
* main.css: Added.
(TestResultsView.setAvailableTests): Added.
(TestResultsView.showTooltip): Fixed the code to compute x and y coordinates of the tooltip to take
scrolled positions into account.
(TestResultsView._createTestResultRow): Extracted from _populateTestPane.
(TestResultsView.fetchTest): Added the code to show "Loading..." in the pane while loading the JSON.
(TestResultsView.fetchTests): Respect the doNotUpdateHash flag.
(TestResultsView._populateBuilderPane): Added.
(TestResultsView.fetchFailingTestsForBuilder): Added.
(TestResultsView.updateLocationHash): Serialize builder & builderDays.
(TestResultsView.locationHashChanged): Don't delete existing test panes since that's now done in
loadTestsFromLocationHash.
(TestResultsView.loadTestsFromLocationHash): Take care of both 'tests' and 'builder' components.
(fetchManifest): Setup the UI to select a builder.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@157659 268f45cc-cd09-0410-ab3c-d52691b4dbfc