Add data-URI support class to dart:core (next to Uri).

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 564 matching lines @@
     "name": "Symbol",
     "kind": "class"
   },
   {
     "name": "Type",
     "kind": "class"
   },
   {
     "name": "Uri",
     "kind": "class"
+  },
+  {
+    "name": "UriData",
+    "kind": "class"
   }
 ];
 
 final object = {
   "name": "Object",
   "kind": "instance side",
   "members": [
     {
       "name": "==",
       "kind": "function",
@@ skipping 12 matching lines @@
       "name": "noSuchMethod",
       "kind": "function",
       "type": "(Invocation) -> dynamic"
     },
     {
       "name": "runtimeType",
       "kind": "getter"
     }
   ]
 };