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

runtime/bin/builtin.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 BIN_BUILTIN_H_
 #define BIN_BUILTIN_H_
 
 #include <stdio.h>
 #include <stdlib.h>
 
@@ skipping 33 matching lines @@
 
   static Dart_Handle LoadLibrary(Dart_Handle url, BuiltinLibraryId id);
   static BuiltinLibraryId FindId(const char* url_string);
 
   // Check if built in library specified in 'id' is already loaded, if not
   // load it.
   static Dart_Handle LoadAndCheckLibrary(BuiltinLibraryId id);
 
   static Dart_Handle SetLoadPort(Dart_Port port);
 
+  static Dart_Port LoadPort() {
+    ASSERT(load_port_ != ILLEGAL_PORT);
+    return load_port_;
+  }
+
  private:
   // Map specified URI to an actual file name from 'source_paths' and read
   // the file.
   static Dart_Handle GetSource(const char** source_paths, const char* uri);
 
   // Native method support.
   static Dart_NativeFunction NativeLookup(Dart_Handle name,
                                           int argument_count,
                                           bool* auto_setup_scope);
 
@@ skipping 27 matching lines @@
   static builtin_lib_props builtin_libraries_[];
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Builtin);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_BUILTIN_H_