Don't attempt to recover from missing strings.

pkg/fasta/test/dart2js_test.dart

Index: pkg/fasta/test/dart2js_test.dart
diff --git a/pkg/fasta/test/dart2js_test.dart b/pkg/fasta/test/dart2js_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..42812a86ad8c10271afba4f1a470ec5c9ad2e261
--- /dev/null
+++ b/pkg/fasta/test/dart2js_test.dart
@@ -0,0 +1,48 @@
+// 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.md file.
+
+library fasta.test.dart2js_test;
+
+import 'package:test_dart/test_configurations.dart' show
+    testConfigurations;
+
+import 'package:test_dart/test_options.dart' show
+    TestOptionsParser;
+
+import 'package:test_dart/test_suite.dart' show
+    TestUtils;
+
+const String arch = "-ax64";
+
+const String mode = "-mrelease";
+
+const String processes = "-j16";
+
+const String dart2jsV8 = "-cdart2js -rd8";
+
+const String common =
+    // --dart2js-batch is ignored unless set in the first configuration.
+    "--dart2js-batch --time -pcolor --report --failure-summary";
+
+main(List<String> arguments) {
+  if (arguments.join(" ") != "--run-tests") {
+    // Protect against being run from test.dart.
+    print("Usage: dart2js_test.dart --run-tests");
+    return;
+  }
+  TestUtils.setDartDirUri(Uri.base);
+  List<String> commandLines = <String>[
+      "--checked dart2js",
+      "$dart2jsV8 --exclude-suite=observatory_ui",
+      "$dart2jsV8 dart2js_extra dart2js_native",
+    ];
+  List<Map> configurations = <Map>[];
+  for (String commandLine in commandLines) {
+    List<String> arguments = <String>[arch, mode, processes]
+        ..addAll("$common $commandLine".split(" "));
+    TestOptionsParser optionsParser = new TestOptionsParser();
+    configurations.addAll(optionsParser.parse(arguments));
+  }
+  testConfigurations(configurations);
+}