revisiting 2 approved test cases

We need to revisit these two previously approved test cases because of the
change to BLD to allow the same symbol with multiple arities. We could just
change them from NegativeSyntax to PositiveSyntax tests (and change the
names).

http://www.w3.org/2005/rules/wiki/No_polymorphic_symbols
http://www.w3.org/2005/rules/wiki/Named_Argument_Uniterms_non-polymorphic

Stella