Introduce code to generate UnlinkedPublicNamespace directly from an AST.

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';
 import 'package:analyzer/src/generated/utilities_dart.dart';
-import 'package:analyzer/src/summary/builder.dart';
+import 'package:analyzer/src/summary/base.dart';
 import 'package:analyzer/src/summary/format.dart';
 
 /**
  * Serialize all the elements in [lib] to a summary using [ctx] as the context
  * for building the summary, and using [typeProvider] to find built-in types.
  */
 LibrarySerializationResult serializeLibrary(
     BuilderContext ctx, LibraryElement lib, TypeProvider typeProvider) {
   var serializer = new _LibrarySerializer(ctx, lib, typeProvider);
   PrelinkedLibraryBuilder prelinked = serializer.serializeLibrary();
@@ skipping 617 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;
   }
 }