anchor.diff:          CpsFragment cps = new CpsFragment(sourceInfo);
           cps.invokeBuiltin(BuiltinMethod.Push,
               list,
  -            <Primitive>[addedItem],
  -            receiverIsNotNull: listValue.isDefinitelyNotNull);
  +            <Primitive>[addedItem]);
           cps.invokeContinuation(cont, [cps.makeNull()]);
           replaceSubtree(node, cps.result);
           push(cps.result);
  
positive.code:     if (specializeClosureCall(node)) return;
  
      AbstractValue receiver = getValue(node.receiver.definition);
      node.receiverIsNotNull = receiver.isDefinitelyNotNull;
  
      if (node.receiverIsIntercepted &&
          node.receiver.definition.sameValue(node.arguments[0].definition)) {
  
negative.code:         CpsFragment cps = new CpsFragment(sourceInfo);
          cps.invokeBuiltin(BuiltinMethod.Push,
              list,
              addedLiteral.values.map((ref) => ref.definition).toList());
          cps.invokeContinuation(cont, [cps.makeNull()]);
          replaceSubtree(node, cps.result);
          push(cps.result);
  