anchor.diff:    }
   
     visitSendSet(SendSet send) {
  -    if (send.selector is Identifier) {
  -      tryMakePrivateIdentifier(send.selector.asIdentifier());
  -    }
       final element = treeElements[send];
       if (element !== null) {
         if (element.isTopLevel()) {
  
positive.code:     }
    }
  
    visitDynamicSend(Send node) {
      Element element = elements[node];
      if (element !== null && element.isErroneous()) return;
      tryRenamePrivateSelector(node);
    }
  
    visitGetterSend(Send node) {
      final element = elements[node];
      // element === null means dynamic property access.
      if (element === null || element.isMember()) {
        tryRenamePrivateSelector(node);
        return;
      }
      // We don't want to rename non top-level element access
      // unless it's a local variable.
      if (element.isPrefix()) {
  
negative.code:       }
      }
      send.visitChildren(this);
    }
  
    visitIdentifier(Identifier identifier) {
      if (identifier.source.isPrivate()) makePrivateIdentifier(identifier);
    }
  
    static bool isPlainTypeName(TypeAnnotation typeAnnotation) {
  