Add UnlinkedClass.hasNoSupertype property to summaries.

pkg/analyzer/lib/src/summary/summarize_elements.dart

 // Copyright (c) 2015, 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 serialization.elements;
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/resolver.dart';
@@ skipping 202 matching lines @@
   }
 
   /**
    * Serialize the given [classElement], creating an [UnlinkedClass].
    */
   UnlinkedClassBuilder serializeClass(ClassElement classElement) {
     UnlinkedClassBuilder b = new UnlinkedClassBuilder(ctx);
     b.name = classElement.name;
     b.typeParameters =
         classElement.typeParameters.map(serializeTypeParam).toList();
-    if (classElement.supertype != null && !classElement.supertype.isObject) {
+    if (classElement.supertype == null) {
+      b.hasNoSupertype = true;
+    } else if (!classElement.supertype.isObject) {
       b.supertype = serializeTypeRef(classElement.supertype, classElement);
     }
     b.mixins = classElement.mixins
         .map((InterfaceType t) => serializeTypeRef(t, classElement))
         .toList();
     b.interfaces = classElement.interfaces
         .map((InterfaceType t) => serializeTypeRef(t, classElement))
         .toList();
     List<UnlinkedVariableBuilder> fields = <UnlinkedVariableBuilder>[];
     List<UnlinkedExecutableBuilder> executables = <UnlinkedExecutableBuilder>[];
@@ skipping 320 matching lines @@
     UnlinkedVariableBuilder b = new UnlinkedVariableBuilder(ctx);
     b.name = variable.name;
     b.type = serializeTypeRef(variable.type, variable);
     b.isStatic = variable.isStatic && variable.enclosingElement is ClassElement;
     b.isFinal = variable.isFinal;
     b.isConst = variable.isConst;
     b.hasImplicitType = variable.hasImplicitType;
     return b;
   }
 }