Add Selection.toString() calling the native method

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 70b05ea6d1928f51ca1f45c88016202aa4b4af75..3062dbee3058e830a286c00379282e60c6c90cdc 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -29277,12 +29277,13 @@ class SelectElement extends HtmlElement {
     }
   }
 }
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2017, 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.
 
+// WARNING: Do not edit - generated code.
+
 
-@DocsEditable()
 @DomName('Selection')
 @Native("Selection")
 class Selection extends Interceptor {
@@ -29398,6 +29399,10 @@ class Selection extends Interceptor {
   @DocsEditable()
   @Experimental() // non-standard
   void setPosition(Node node, [int offset]) native;
+
+  @DomName('Selection.toString')
+  @DocsEditable()
+  String toString() native;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a