Fix a bug in nested context code that occured when calling a function nested in the outermost scope with a context frame from a function using a more nested context frame.

module typeinfo5;

void main()
{
    enum E : uint {
        A,B,C
    }
    auto ti = typeid(E);
    assert(ti.next() is typeid(uint));
    assert(ti.init is null);
}