Revert "Remove 'Element.docRange'."

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

 // Copyright (c) 2016, 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.summarize_ast;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/type.dart' show DartType;
@@ skipping 567 matching lines @@
    */
   UnlinkedDocumentationCommentBuilder serializeDocumentation(
       Comment documentationComment) {
     if (documentationComment == null) {
       return null;
     }
     String text = documentationComment.tokens
         .map((Token t) => t.toString())
         .join()
         .replaceAll('\r\n', '\n');
-    return new UnlinkedDocumentationCommentBuilder(text: text);
+    return new UnlinkedDocumentationCommentBuilder(
+        text: text,
+        offset: documentationComment.offset,
+        length: documentationComment.length);
   }
 
   /**
    * Serialize a [FunctionDeclaration] or [MethodDeclaration] into an
    * [UnlinkedExecutable].
    *
    * If [serializeBodyExpr] is `true`, then the function definition is stored
    * in [UnlinkedExecutableBuilder.bodyExpr].
    */
   UnlinkedExecutableBuilder serializeExecutable(
@@ skipping 775 matching lines @@
 /**
  * A [_TypeParameterScope] is a [_Scope] which defines [_ScopedTypeParameter]s.
  */
 class _TypeParameterScope extends _Scope {
   /**
    * Get the number of [_ScopedTypeParameter]s defined in this
    * [_TypeParameterScope].
    */
   int get length => _definedNames.length;
 }