Because the observer for _updateSuggestions was setup without declaring
all the properties it depended on, and since the one declared dependency
was set statically, the observer would fire before the element was ready
and frequently before all the dependencies were setup.
Make the property dependencies explicit so that the observer executes at
the expected time.
Bug: Issue 8149
Change-Id: I9fff4d0a9c563afa9cd4559fa63061a3749cb9cf
2fa1d08ce4