Add summary support for ShowElementCombinator.end and .offset.

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/element.dart';
 import 'package:analyzer/src/dart/element/member.dart';
@@ skipping 475 matching lines @@
   }
 
   /**
    * Serialize the given [combinator] into an [UnlinkedCombinator].
    */
   UnlinkedCombinatorBuilder serializeCombinator(
       NamespaceCombinator combinator) {
     UnlinkedCombinatorBuilder b = new UnlinkedCombinatorBuilder();
     if (combinator is ShowElementCombinator) {
       b.shows = combinator.shownNames;
+      b.offset = combinator.offset;
+      b.end = combinator.end;
     } else if (combinator is HideElementCombinator) {
       b.hides = combinator.hiddenNames;
     }
     return b;
   }
 
   /**
    * Serialize the given [expression], creating an [UnlinkedConstBuilder].
    */
   UnlinkedConstBuilder serializeConstExpr(Expression expression,
@@ skipping 927 matching lines @@
       exportNames.add(new LinkedExportNameBuilder(
           name: name,
           dependency: serializeDependency(dependentLibrary),
           unit: unit,
           kind: kind));
     }
     pb.exportNames = exportNames;
     return pb;
   }
 }