Rename [TreatNonCallableAsNull] to [TreatNonObjectAsNull] and change its semantics to allow setting non-callable objects but no-op the call to them.  See thread starting http://lists.w3.org/Archives/Public/public-script-coord/2013OctDec/0405.html
Merge pull request #7 from bzbarsky/TreatNonObjectAsNull

Rename [TreatNonCallableAsNull] to [TreatNonObjectAsNull] and change its semantics to allow setting non-callable objects but no-op the call to them.