re PR c++/84596 (internal compiler error: unexpected expression '(bool)c' of kind implicit_conv_expr (cxx_eval_constant_expression))

	PR c++/84596
	* semantics.c (finish_static_assert): Check
	instantiation_dependent_expression_p instead of
	{type,value}_dependent_expression_p.

	* g++.dg/cpp0x/static_assert15.C: New test.

From-SVN: r258513