Fix some assertion failures on Fuchsia

runtime/bin/gen_snapshot.cc

 // Copyright (c) 2013, 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.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 1532 matching lines @@
     exit(kErrorExitCode);
   }
 
   Dart_Handle result;
   Dart_Handle library;
   Dart_EnterScope();
 
   result = Dart_SetEnvironmentCallback(EnvironmentCallback);
   CHECK_RESULT(result);
 
-  ASSERT(vm_snapshot_data_filename != NULL);
-  ASSERT(isolate_snapshot_data_filename != NULL);
   // Load up the script before a snapshot is created.
   if (app_script_name != NULL) {
     // This is the case of a custom embedder (e.g: dartium) trying to
     // create a full snapshot. The current isolate is set up so that we can
     // invoke the dart uri resolution code like _resolveURI. App script is
     // loaded into a separate isolate.
     SetupForUriResolution();
 
     // Prepare builtin and its dependent libraries for use to resolve URIs.
     // Set up various closures, e.g: printing, timers etc.
@@ skipping 129 matching lines @@
   delete mapped_isolate_snapshot_data;
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }