Undeclared static setter calls: Compile time error becomes static warning per spec, 10.16

Spec section 10.16 has changed its handling of static setters (assignment)

It is a static warning if there is no class C in the enclosing lexical scope of the assignment, or if C does not declare, implicitly or explicitly, a setter v.

So, what was once a compile-time error is now a warning. 
