R1:2d635fb76e9b

Dashboard Panel: fix first tab sometime not opened anymore

Summary:
After this change the first Tab ID is always selected, so we don't risk
to have no tabs opened by default under some corner cases.

This is vaguely better than the original logic that relied on the fact that
(0=="0") is true. Besides being a vaguely weird emoticon as well, now that
I look at it better.

Original logic:

https://we.phorge.it/source/phorge/browse/master/src/applications/dashboard/paneltype/PhabricatorDashboardTabsPanelType.