anchor.diff:          null;
     }
   
  +  @override
  +  void registerNodeProcessors(
  +      NodeLintRegistry registry, LinterContext context) {
  +    bool hasFlutter(String root) {
  +      var hasFlutter = _rootHasFlutterCache[root];
  +      if (hasFlutter == null) {
  +        // clear previous cache
  +        _rootHasFlutterCache.clear();
  +        var pubspecFile = locatePubspecFile(context.currentUnit.unit);
  +        hasFlutter = hasFlutterDep(pubspecFile);
  +        _rootHasFlutterCache[root] = hasFlutter;
  +      }
  +      return hasFlutter;
  +    }
  +
  +    var root = context.package?.root;
  +    if (root != null) {
  +      if (hasFlutter(root)) {
  +        var visitor = _Visitor(this);
  +        registry.addImportDirective(this, visitor);
  +      }
  +    }
  +  }
  +}
  +
  +class _Visitor extends SimpleAstVisitor<void> {
  +  final LintRule rule;
  +
  +  _Visitor(this.rule);
  +
     bool isWebUri(String uri) {
       var uriLength = uri.length;
       return (uriLength == 9 && uri == 'dart:html') ||
  
positive.code:             maturity: Maturity.stable,
              group: Group.errors);
  
    @override
    void registerNodeProcessors(
        NodeLintRegistry registry, LinterContext context) {
      var visitor = _Visitor(this);
      registry.addCompilationUnit(this, visitor);
      registry.addImportDirective(this, visitor);
    }
  }
  
  class _Visitor extends SimpleAstVisitor<void> {
    File? pubspecFile;
  
    final LintRule rule;
    bool? _shouldValidateUri;
  
    _Visitor(this.rule);
  
    bool get shouldValidateUri => _shouldValidateUri ??= checkForValidation();
  
    bool checkForValidation() {
      var file = pubspecFile;
      if (file == null) {
        return false;
      }
  
      YamlMap parsedPubspec;
      try {
        var content = file.readAsStringSync();
        parsedPubspec = _parseYaml(content);
        // ignore: avoid_catches_without_on_clauses
      } catch (_) {
  
negative.code:   }
  
    @override
    void visitImportDirective(ImportDirective node) {
      var uriString = node.uri.stringValue;
      if (uriString != null && isWebUri(uriString)) {
        rule.reportLint(node);
      }
    }
  }
  