Very simple version of Isolates.

runtime/vm/bootstrap_natives.h

 // 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.
 
 #ifndef VM_BOOTSTRAP_NATIVES_H_
 #define VM_BOOTSTRAP_NATIVES_H_
 
 #include "vm/native_entry.h"
 
 // bootstrap dart natives used in the core dart library.
@@ skipping 231 matching lines @@
   V(Uint32x4_getFlagX, 1)                                                      \
   V(Uint32x4_getFlagY, 1)                                                      \
   V(Uint32x4_getFlagZ, 1)                                                      \
   V(Uint32x4_getFlagW, 1)                                                      \
   V(Uint32x4_setFlagX, 2)                                                      \
   V(Uint32x4_setFlagY, 2)                                                      \
   V(Uint32x4_setFlagZ, 2)                                                      \
   V(Uint32x4_setFlagW, 2)                                                      \
   V(Uint32x4_select, 3)                                                        \
   V(isolate_getPortInternal, 0)                                                \
-  V(isolate_spawnFunction, 2)                                                  \
+  V(isolate_spawnFunction, 1)                                                  \
   V(isolate_spawnUri, 1)                                                       \
   V(Mirrors_isLocalPort, 1)                                                    \
   V(Mirrors_makeLocalClassMirror, 1)                                           \
   V(Mirrors_makeLocalTypeMirror, 1)                                            \
   V(Mirrors_makeLocalMirrorSystem, 0)                                          \
   V(Mirrors_mangleName, 2)                                                     \
   V(Mirrors_unmangleName, 1)                                                   \
   V(MirrorReference_equals, 2)                                                 \
   V(InstanceMirror_invoke, 5)                                                  \
   V(InstanceMirror_invokeGetter, 3)                                            \
@@ skipping 54 matching lines @@
   static void DN_##name(Dart_NativeArguments args);
 
   BOOTSTRAP_NATIVE_LIST(DECLARE_BOOTSTRAP_NATIVE)
 
 #undef DECLARE_BOOTSTRAP_NATIVE
 };
 
 }  // namespace dart
 
 #endif  // VM_BOOTSTRAP_NATIVES_H_