Add support for Element.docRange to the summary.

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 373 matching lines @@
    * Serialize documentation from the given [element], creating an
    * [UnlinkedDocumentationComment].
    *
    * If [element] has no documentation, `null` is returned.
    */
   UnlinkedDocumentationCommentBuilder serializeDocumentation(Element element) {
     if (element.documentationComment == null) {
       return null;
     }
     return encodeUnlinkedDocumentationComment(ctx,
-        text: element.documentationComment);
+        text: element.documentationComment,
+        offset: element.docRange.offset,
+        length: element.docRange.length);
   }
 
   /**
    * Return the index of the entry in the references table
    * ([UnlinkedLibrary.references] and [PrelinkedLibrary.references])
    * representing the pseudo-type `dynamic`.
    */
   int serializeDynamicReference() => 0;
 
   /**
@@ skipping 294 matching lines @@
     b.nameOffset = variable.nameOffset;
     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;
     b.documentationComment = serializeDocumentation(variable);
     return b;
   }
 }