build.webkit.org/dashboard unnecessarily loads results of hidden queues

build.webkit.org/dashboard unnecessarily loads results of hidden queues
https://bugs.webkit.org/show_bug.cgi?id=136195

Reviewed by Tim Horton.

This patch also makes it possible to avoid any automatic loading, as needed for metrics view.

* BuildSlaveSupport/build.webkit.org-config/public_html/dashboard/Scripts/BuildbotQueue.js:
* BuildSlaveSupport/build.webkit.org-config/public_html/dashboard/Scripts/EWSQueue.js:
Don't start an update just because a queue object was created. Periodic updates
are triggered by views, so it only makes sense to do the same for the initial update.

* BuildSlaveSupport/build.webkit.org-config/public_html/dashboard/Scripts/Main.js:
Now that Trac object doesn't auto-load, start loading here.

* BuildSlaveSupport/build.webkit.org-config/public_html/dashboard/Scripts/QueueView.js:
(QueueView): Calling _updateHiddenState right away was wrong, because it accesses
a data member added by subclasses later. With this.platform being undefined, it
always looked like this queue was not hidden.
(QueueView.prototype._updateHiddenState): Start an immediate update, too.

* BuildSlaveSupport/build.webkit.org-config/public_html/dashboard/Scripts/Trac.js:
(Trac): Don't load anything here, the client may choose to load a custom date range.
(Trac.prototype.startPeriodicUpdates): Added a function to start automatic loading.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@172893 268f45cc-cd09-0410-ab3c-d52691b4dbfc