Add AnalysisSession to analyzer

pkg/analyzer/lib/dart/analysis/results.dart

Index: pkg/analyzer/lib/dart/analysis/results.dart
diff --git a/pkg/analyzer/lib/dart/analysis/results.dart b/pkg/analyzer/lib/dart/analysis/results.dart
index 8954f4f5d1e1cdb465e6a6d3220d7b9982edd17c..91fd27c89f9d1d36433b0e216f19e6e07288d310 100644
--- a/pkg/analyzer/lib/dart/analysis/results.dart
+++ b/pkg/analyzer/lib/dart/analysis/results.dart
@@ -2,6 +2,7 @@
 // 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.
 
+import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/error/error.dart';
@@ -21,6 +22,11 @@ abstract class AnalysisResult {
   String get path;
 
   /**
+   * Return the session used to compute this result.
+   */
+  AnalysisSession get session;
+
+  /**
    * The state of the results.
    */
   ResultState get state;