[Bug 3603695]: Change the way that the [oo::object] 'varname' method is implemented so that there are no longer problems with interactions due to the resolver. Thanks to Taylor Venable <tcvena@gmail.com> for identifying the problem.

Note that due to some subtleties, this test was not failing in the packaged
version of TclOO. The code is backported anyway though, as it is rather cleaner
than the previous version.