Fix for issue 23598, add a Dart_CreateLibrarySnapshot entrypoint to the API.

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 1038 matching lines @@
  *   the snapshot. This buffer is scope allocated and is only valid
  *   until the next call to Dart_ExitScope.
  * \param size Returns the size of the buffer.
  *
  * \return A valid handle if no error occurs during the operation.
  */
 DART_EXPORT Dart_Handle Dart_CreateScriptSnapshot(uint8_t** buffer,
                                                   intptr_t* size);
 
 /**
+ * Creates a snapshot of the specified library loaded in the isolate.
+ *
+ * A library snapshot can be used for implementing fast startup of applications
+ * (skips tokenizing and parsing process). A Snapshot of the library
+ * can only be created before any dart code has executed.
+ *
+ * Requires there to be a current isolate which already has loaded the library.
+ *
+ * \param library A library for which the snapshot needs to be created.
+ * \param buffer Returns a pointer to a buffer containing
+ *   the snapshot. This buffer is scope allocated and is only valid
+ *   until the next call to Dart_ExitScope.
+ * \param size Returns the size of the buffer.
+ *
+ * \return A valid handle if no error occurs during the operation.
+ */
+DART_EXPORT Dart_Handle Dart_CreateLibrarySnapshot(Dart_Handle library,
+                                                   uint8_t** buffer,
+                                                   intptr_t* size);
+
+/**
  * Schedules an interrupt for the specified isolate.
  *
  * When the isolate is interrupted, the isolate interrupt callback
  * will be invoked with 'isolate' as the current isolate (see
  * Dart_IsolateInterruptCallback).
  *
  * \param isolate The isolate to be interrupted.
  */
 DART_EXPORT void Dart_InterruptIsolate(Dart_Isolate isolate);
 
@@ skipping 1799 matching lines @@
  * NOTE: If multiple callbacks with the same name are registered, only
  * the last callback registered will be remembered.
  */
 DART_EXPORT void Dart_RegisterRootServiceRequestCallback(
     const char* method,
     Dart_ServiceRequestCallback callback,
     void* user_data);
 
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */