Serialize / resynthesize 'isAsynchronous' and 'isGenerator' flags.

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 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 776 matching lines @@
                       initializer,
                       (expr) => serializeConstExpr(
                           executableElement, expr, constructorParameterNames)))
               .toList();
         }
       }
     } else {
       b.kind = UnlinkedExecutableKind.functionOrMethod;
     }
     b.isAbstract = executableElement.isAbstract;
+    b.isAsynchronous = executableElement.isAsynchronous;
+    b.isGenerator = executableElement.isGenerator;
     b.isStatic = executableElement.isStatic &&
         executableElement.enclosingElement is ClassElement;
     b.isExternal = executableElement.isExternal;
     b.documentationComment = serializeDocumentation(executableElement);
     b.annotations = serializeAnnotations(executableElement);
     b.codeRange = serializeCodeRange(executableElement);
     if (executableElement is FunctionElement) {
       SourceRange visibleRange = executableElement.visibleRange;
       if (visibleRange != null) {
         b.visibleOffset = visibleRange.offset;
@@ skipping 859 matching lines @@
       exportNames.add(new LinkedExportNameBuilder(
           name: name,
           dependency: serializeDependency(dependentLibrary),
           unit: unit,
           kind: kind));
     }
     pb.exportNames = exportNames;
     return pb;
   }
 }