Add an assertion to ensure that the return type and types of parameters are canonical or a TypeParam

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 <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ skipping 498 matching lines @@
     const char* err_msg = Dart_GetError(library);
     Log::PrintErr("Errors encountered while loading: %s\n", err_msg);
     Dart_ExitScope();
     Dart_ShutdownIsolate();
     exit(255);
   }
 }
 
 
 int main(int argc, char** argv) {
-  const int EXTRA_VM_ARGUMENTS = 1;
+  const int EXTRA_VM_ARGUMENTS = 2;
   CommandLineOptions vm_options(argc + EXTRA_VM_ARGUMENTS);
 
   // Initialize the URL mapping array.
   CommandLineOptions url_mapping_array(argc);
   url_mapping = &url_mapping_array;
 
   // Parse command line arguments.
   if (ParseArguments(argc,
                      argv,
                      &vm_options,
                      &app_script_name) < 0) {
     PrintUsage();
     return 255;
   }
 
   Thread::InitOnce();
   DartUtils::SetOriginalWorkingDirectory();
 
   vm_options.AddArgument("--load_deferred_eagerly");
-
+  // Workaround until issue 21620 is fixed.
+  // (https://github.com/dart-lang/sdk/issues/21620)
+  vm_options.AddArgument("--no-concurrent_sweep");
   Dart_SetVMFlags(vm_options.count(), vm_options.arguments());
 
   // Initialize the Dart VM.
   // Note: We don't expect isolates to be created from dart code during
   // snapshot generation.
   if (!Dart_Initialize(NULL,
                        NULL, NULL, NULL, NULL,
                        DartUtils::OpenFile,
                        DartUtils::ReadFile,
                        DartUtils::WriteFile,
@@ skipping 78 matching lines @@
   }
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }