anchor.diff:      // If the nullability is explicitly nullable, that is, if the type parameter
       // type is followed by '?' in the code, the nullability of the type is
       // 'nullable.'
  -    if (nullability == Nullability.nullable) {
  +    if (declaredNullability == Nullability.nullable) {
         lhsNullability = Nullability.nullable;
       } else {
         // If the bound is nullable, both nullable and non-nullable types can be
  
positive.code: /// is the same as the [TypeParameter]'s bound.  This allows one to detect
  /// whether the bound has been promoted.
  class TypeParameterType extends DartType {
    final Nullability nullability;
  
    TypeParameter parameter;
  
negative.code:   DartType promotedBound;
  
    TypeParameterType(this.parameter,
        [this.promotedBound, this.declaredNullability])
        : this.nullability =
              getNullability(parameter, promotedBound, declaredNullability);
  
    accept(DartTypeVisitor v) => v.visitTypeParameterType(this);
    accept1(DartTypeVisitor1 v, arg) => v.visitTypeParameterType(this, arg);
  