Revert "Hide Isolate pointer from embedder"

runtime/lib/isolate.cc

 // 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.
 
 #include "platform/assert.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 154 matching lines @@
 static bool CreateIsolate(Isolate* parent_isolate,
                           IsolateSpawnState* state,
                           char** error) {
   Dart_IsolateCreateCallback callback = Isolate::CreateCallback();
   if (callback == NULL) {
     *error = strdup("Null callback specified for isolate creation\n");
     return false;
   }
 
   void* init_data = parent_isolate->init_callback_data();
-  Isolate* child_isolate = Api::CastIsolate((callback)(state->script_url(),
-                                                       state->function_name(),
-                                                       state->package_root(),
-                                                       init_data,
-                                                       error));
+  Isolate* child_isolate = reinterpret_cast<Isolate*>(
+      (callback)(state->script_url(),
+                 state->function_name(),
+                 state->package_root(),
+                 init_data,
+                 error));
   if (child_isolate == NULL) {
     return false;
   }
   if (!state->is_spawn_uri()) {
     // For isolates spawned using the spawnFunction semantics we set
     // the origin_id to the origin_id of the parent isolate.
     child_isolate->set_origin_id(parent_isolate->origin_id());
   }
   state->set_isolate(reinterpret_cast<Isolate*>(child_isolate));
   return true;
@@ skipping 111 matching lines @@
   MessageWriter writer(&data, &allocator, false);
   writer.WriteMessage(msg);
 
   PortMap::PostMessage(new Message(port.Id(),
                                    data, writer.BytesWritten(),
                                    Message::kOOBPriority));
   return Object::null();
 }
 
 }  // namespace dart