Add Dart_PostPriority function to dart_api, and use it in runAsync to schedule immediate events in …

runtime/include/dart_api.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 INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
@@ skipping 994 matching lines @@
  * Requires there to be a current isolate.
  *
  * \param port The destination port.
  * \param object An object from the current isolate.
  *
  * \return True if the message was posted.
  */
 DART_EXPORT bool Dart_Post(Dart_Port port_id, Dart_Handle object);
 
 /**
+ * Posts a message for some isolate. The message is a serialized
+ * object. The message is prioritized before other messages.
+ *
+ * Requires there to be a current isolate.
+ *
+ * \param port The destination port.
+ * \param object An object from the current isolate.
+ *
+ * \return True if the message was posted.
+ */
+DART_EXPORT bool Dart_PostPriority(Dart_Port port_id, Dart_Handle object);
+
+/**
  * Returns a new SendPort with the provided port id.
  */
 DART_EXPORT Dart_Handle Dart_NewSendPort(Dart_Port port_id);
 
 /**
  * Gets the ReceivePort for the provided port id, creating it if necessary.
  *
  * Note that there is at most one ReceivePort for a given port id.
  */
 DART_EXPORT Dart_Handle Dart_GetReceivePort(Dart_Port port_id);
@@ skipping 1256 matching lines @@
  *
  * \param object An object.
  * \param peer A value to store in the peer field.
  *
  * \return Returns an error if 'object' is a subtype of Null, num, or
  *   bool.
  */
 DART_EXPORT Dart_Handle Dart_SetPeer(Dart_Handle object, void* peer);
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */