Revert "Hide Isolate pointer from embedder"

runtime/vm/native_api_impl.cc

 // Copyright (c) 2013, 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 "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_message.h"
 #include "vm/dart_api_state.h"
@@ skipping 26 matching lines @@
 
 DART_EXPORT Dart_Port Dart_NewNativePort(const char* name,
                                          Dart_NativeMessageHandler handler,
                                          bool handle_concurrently) {
   if (name == NULL) {
     name = "<UnnamedNativePort>";
   }
   if (handler == NULL) {
     OS::PrintErr("%s expects argument 'handler' to be non-null.\n",
                  CURRENT_FUNC);
-    return DART_ILLEGAL_PORT;
+    return ILLEGAL_PORT;
   }
   // Start the native port without a current isolate.
   IsolateSaver saver(Isolate::Current());
   Thread::ExitIsolate();
 
   NativeMessageHandler* nmh = new NativeMessageHandler(name, handler);
   Dart_Port port_id = PortMap::CreatePort(nmh);
   nmh->Run(Dart::thread_pool(), NULL, NULL, 0);
   return port_id;
 }
@@ skipping 28 matching lines @@
   Dart_Handle result = Api::CheckAndFinalizePendingClasses(isolate);
   if (::Dart_IsError(result)) {
     return result;
   }
   CHECK_CALLBACK_STATE(isolate);
   CompileAll(isolate, &result);
   return result;
 }
 
 }  // namespace dart