anchor.diff:        _writeProperty("element", node.element);
       } else if (node is ExportDirective) {
         _writeProperty("element", node.element);
  +      _writeProperty("source", node.source);
       } else if (node is FunctionExpressionInvocation) {
         _writeProperty('static element', node.staticElement);
         _writeProperty('static type', node.staticType);
  
positive.code: import 'package:analyzer/src/generated/ast.dart';
  import 'package:analyzer/src/generated/element.dart';
  import 'package:analyzer/src/generated/java_engine.dart';
  
  /**
   * A visitor that will produce an HTML representation of an AST structure.
  
negative.code:     if (value != null) {
        String valueString = null;
        try {
          if (value is Source) {
            valueString = 'Source (uri="${value.uri}", path="${value.fullName}")';
          } else {
            valueString = value.toString();
          }
        } catch (exception, stackTrace) {
          exceptions.add(new CaughtException(exception, stackTrace));
        }
  