anchor.diff:  
     @override
     void visitArgumentList(ArgumentList node) {
  -    String context = _argumentListContext(node);
  +    var context = _argumentListContext(node);
  +    var parent = node.parent;
  +    var inWidgetConstructor = parent is InstanceCreationExpression &&
  +        flutter.isWidgetType(parent.staticType);
       for (var argument in node.arguments) {
  +      var realArgument = argument;
  +      var argumentKind = 'unnamed';
         if (argument is NamedExpression) {
  -        _recordDataForNode('ArgumentList (all, named)', argument.expression,
  +        realArgument = argument.expression;
  +        argumentKind = 'named';
  +      }
  +      _recordDataForNode('ArgumentList (all, $argumentKind)', realArgument,
  +          allowedKeywords: expressionKeywords);
  +      _recordDataForNode('ArgumentList ($context, $argumentKind)', realArgument,
  +          allowedKeywords: expressionKeywords);
  +      _recordTypeMatch(realArgument);
  +      if (inWidgetConstructor) {
  +        _recordDataForNode(
  +            'ArgumentList (widget constructor, $argumentKind)', realArgument,
               allowedKeywords: expressionKeywords);
  -        _recordDataForNode(
  -            'ArgumentList ($context, named)', argument.expression,
  -            allowedKeywords: expressionKeywords);
  -        _recordTypeMatch(argument.expression);
  -      } else {
  -        _recordDataForNode('ArgumentList (all, unnamed)', argument,
  -            allowedKeywords: expressionKeywords);
  -        _recordDataForNode('ArgumentList ($context, unnamed)', argument,
  -            allowedKeywords: expressionKeywords);
  -        _recordTypeMatch(argument);
         }
       }
       super.visitArgumentList(node);
  
positive.code: 
    /// Write a report of the metrics that were computed to the [sink].
    void writeMetrics(StringSink sink) {
      sink.writeln('');
      _writeSideBySide(sink, [data.byTokenType, data.byElementKind],
          ['Token Types', 'Element Kinds']);
      sink.writeln('');
      sink.writeln('Type relationships');
      _writeContextMap(sink, data.byTypeMatch);
      sink.writeln('');
      sink.writeln('Structural indicators');
      _writeContextMap(sink, data.byDistance);
  
negative.code: import 'package:_fe_analyzer_shared/src/base/syntactic_entity.dart';
  import 'package:analysis_server/src/protocol_server.dart'
      show convertElementToElementKind, ElementKind;
  import 'package:analysis_server/src/utilities/flutter.dart';
  import 'package:analyzer/dart/analysis/analysis_context_collection.dart';
  import 'package:analyzer/dart/analysis/results.dart';
  import 'package:analyzer/dart/ast/ast.dart';
  