Always provide a field for context.

pkg/front_end/test/fasta/bootstrap_test.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async' show Future;
 
 import 'dart:io' show Directory, Platform;
 
 import 'dart:isolate' show Isolate;
 
@@ skipping 28 matching lines @@
 Future runCompiler(Uri compiler, Uri input, Uri output) async {
   Uri patchedSdk = await computePatchedSdk();
   Uri dartVm = Uri.base.resolve(Platform.resolvedExecutable);
   StdioProcess result = await StdioProcess.run(dartVm.toFilePath(), <String>[
     compiler.toFilePath(),
     "--compile-sdk=${patchedSdk.toFilePath()}",
     "--output=${output.toFilePath()}",
     input.toFilePath(),
   ]);
   print(result.output);
-  if (result.exitCode != 1) {
-    // TODO(ahe): Due to known errors in the VM's patch files, this compiler
-    // should report an error. Also, it may not be able to compile everything
-    // yet.
+  if (result.exitCode != 0) {
     throw "Compilation failed.";
   }
 }