Fix try/poi/serialize_test after adding class to dart:core.

tests/try/poi/serialize_test.dart

 // Copyright (c) 2014, 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.
 
 /// Test that poi.dart can serialize a scope.
 
 library trydart.serialize_test;
 
 import 'dart:io' show
     Platform;
@@ skipping 380 matching lines @@
   },
   {
     "name": "ArgumentError",
     "kind": "class"
   },
   {
     "name": "RangeError",
     "kind": "class"
   },
   {
+    "name": "IndexError",
+    "kind": "class"
+  },
+  {
     "name": "FallThroughError",
     "kind": "class"
   },
   {
     "name": "AbstractClassInstantiationError",
     "kind": "class"
   },
   {
     "name": "NoSuchMethodError",
     "kind": "class"
@@ skipping 185 matching lines @@
       "name": "noSuchMethod",
       "kind": "function",
       "type": "(Invocation) -> dynamic"
     },
     {
       "name": "runtimeType",
       "kind": "getter"
     }
   ]
 };