Disable the Javascript profiler while there is no data available.

With V4 the Javascript profiler is unusable. In order not to suggest to
the user that it is actually usable, we disable it if it doesn't show
any data. However, when profiling applications that don't use V4, yet,
the JS profiler actually works and has to be enabled.

Change-Id: Iecb97c0940addd157c5ebe229edb614448cc0554
Reviewed-by: Kai Koehne <kai.koehne@digia.com>