This change marks the WIP dashboard section to be hidden when empty by
supplying the hideIfEmpty property. In a descendant change, another
dashboard section will be added that uses the query `has:draft` -- this
will resolve issue 9448.
Also contains a minor refactoring of gr-dashboard-view.js for better
testability.
Bug: Issue 9448, Issue 8340, Issue 9034
Change-Id: I252e8de55aebf33dc51606f3f613faf4f4d985b8