Add `packages` parameter to `Isolate.spawnUri`.

runtime/lib/isolate_patch.dart

 // 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
 // BSD-style license that can be found in the LICENSE file.
 
 import "dart:collection" show HashMap;
 import "dart:_internal";
 
 patch class ReceivePort {
   /* patch */ factory ReceivePort() = _ReceivePortImpl;
 
@@ skipping 288 matching lines @@
     } catch (e, st) {
       if (readyPort != null) {
         readyPort.close();
       }
       return new Future<Isolate>.error(e, st);
     }
   }
 
   /* patch */ static Future<Isolate> spawnUri(
       Uri uri, List<String> args, var message,
-      {bool paused: false, bool checked, Uri packageRoot, bool errorsAreFatal,
-       SendPort onExit, SendPort onError}) {
+      {bool paused: false,
+       bool checked,
+       Uri packageRoot,
+       Map<String, Uri> packages,
+       bool errorsAreFatal,
+       SendPort onExit,
+       SendPort onError}) {
     RawReceivePort readyPort;
     try {
       // The VM will invoke [_startIsolate] and not `main`.
+      // TODO: Handle [packages].
       readyPort = new RawReceivePort();
       var packageRootString =
           (packageRoot == null) ? null : packageRoot.toString();
       _spawnUri(readyPort.sendPort, uri.toString(), args, message,
                 paused, checked, packageRootString,
                 errorsAreFatal, onExit, onError);
       Completer completer = new Completer<Isolate>.sync();
       readyPort.handler = (readyMessage) {
         readyPort.close();
         assert(readyMessage is List);
@@ skipping 125 matching lines @@
   static Isolate _getCurrentIsolate() {
     List portAndCapabilities = _getPortAndCapabilitiesOfCurrentIsolate();
     return new Isolate(portAndCapabilities[0],
                        pauseCapability: portAndCapabilities[1],
                        terminateCapability: portAndCapabilities[2]);
   }
 
   static List _getPortAndCapabilitiesOfCurrentIsolate()
       native "Isolate_getPortAndCapabilitiesOfCurrentIsolate";
 }