Rework standalone to use a synchronous loader that does not invoke Dart code

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 2638 matching lines @@
 
 
 /*
  * =====================
  * Scripts and Libraries
  * =====================
  */
 /* TODO(turnidge): Finish documenting this section. */
 
 typedef enum {
-  Dart_kImportTag = 0,
+  Dart_kCanonicalizeUrl = 0,
+  Dart_kScriptTag,
   Dart_kSourceTag,
-  Dart_kCanonicalizeUrl,
-  Dart_kScriptTag,
+  Dart_kImportTag,
 } Dart_LibraryTag;
 
 /* TODO(turnidge): Document. */
 typedef Dart_Handle (*Dart_LibraryTagHandler)(Dart_LibraryTag tag,
                                               Dart_Handle library,
                                               Dart_Handle url);
 
 /**
  * Sets library tag handler for the current isolate. This handler is
  * used to handle the various tags encountered while loading libraries
@@ skipping 398 matching lines @@
 /**
  *  Returns whether the VM was initialized with a precompiled snapshot. Only
  *  valid after Dart_Initialize.
  *  DEPRECATED. This is currently used to disable Platform.executable and
  *  Platform.resolvedExecutable under precompilation to prevent process
  *  spawning tests from becoming fork-bombs.
  */
 DART_EXPORT bool Dart_IsRunningPrecompiledCode();
 
 #endif  /* INCLUDE_DART_API_H_ */  /* NOLINT */