Add flag to track if a constructor is the synthetic default constructor.

pkg/analyzer/lib/src/kernel/loader.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library kernel.analyzer.loader;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io' as io;
 
 import 'package:analyzer/analyzer.dart';
@@ skipping 508 matching lines @@
               isAbstract: false,
               isStatic: true,
               isExternal: constructor.isExternal,
               isConst: constructor.isConst,
               fileUri: '${element.source.uri}')
             ..fileOffset = element.nameOffset;
         }
         return new ast.Constructor(scope.buildFunctionInterface(constructor),
             name: _nameOfMember(element),
             isConst: constructor.isConst,
-            isExternal: constructor.isExternal)
+            isExternal: constructor.isExternal,
+            isSyntheticDefault: constructor.isSynthetic)
           ..fileOffset = element.nameOffset;
 
       case ElementKind.FIELD:
       case ElementKind.TOP_LEVEL_VARIABLE:
         VariableElement variable = element;
         return new ast.Field(_nameOfMember(variable),
             isStatic: variable.isStatic,
             isFinal: variable.isFinal,
             isConst: variable.isConst,
             type: scope.buildType(variable.type),
@@ skipping 462 matching lines @@
   AnalysisContext context = AnalysisEngine.instance.createAnalysisContext()
     ..sourceFactory = new SourceFactory(resolvers)
     ..analysisOptions = createAnalysisOptions(options.strongMode);
 
   options.declaredVariables.forEach((String name, String value) {
     context.declaredVariables.define(name, value);
   });
 
   return context;
 }