Don't use async loading in gen_snapshot.

runtime/bin/dartutils.cc

 // 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.
 
 #include "bin/dartutils.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
@@ skipping 576 matching lines @@
   Dart_Handle res = Dart_FinalizeLoading(true);
   if (Dart_IsError(res)) {
     // TODO(hausner): If compilation/loading errors are supposed to
     // be observable by the program, we need to mark the bad library
     // with the error instead of propagating it.
     Dart_PropagateError(res);
   }
 }
 
 
-Dart_Handle DartUtils::LoadSourceAsync(Dart_Handle library,
-                                       Dart_Handle url,
-                                       Dart_LibraryTag tag,
-                                       Dart_Handle builtin_lib) {
-  return LoadDataAsync_Invoke(Dart_NewInteger(tag), url, library, builtin_lib);
-}
-
-
 Dart_Handle DartUtils::PrepareForScriptLoading(const char* package_root,
                                                Dart_Handle builtin_lib) {
   // First ensure all required libraries are available.
   Dart_Handle url = NewString(kAsyncLibURL);
   DART_CHECK_VALID(url);
   Dart_Handle async_lib = Dart_LookupLibrary(url);
   DART_CHECK_VALID(async_lib);
   Dart_Handle io_lib = Builtin::LoadAndCheckLibrary(Builtin::kIOLibrary);
 
   // We need to ensure that all the scripts loaded so far are finalized
@@ skipping 368 matching lines @@
       new CObjectString(CObject::NewString(os_error->message()));
   CObjectArray* result = new CObjectArray(CObject::NewArray(3));
   result->SetAt(0, new CObjectInt32(CObject::NewInt32(kOSError)));
   result->SetAt(1, new CObjectInt32(CObject::NewInt32(os_error->code())));
   result->SetAt(2, error_message);
   return result;
 }
 
 }  // namespace bin
 }  // namespace dart