Don’t exit prematurely if compilation failed.

dart/tests/compiler/dart2js_extra/LayoutTests_fast_mediastream_getusermedia_t01_test.dart

+// Copyright (c) 2015, 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.
+
+/// Test derived from a broken co19 test
+/// (LayoutTests/fast/mediastream/getusermedia_t01.dart). Caused dart2js to
+/// crash.
+
+foo() {}
+
+gotStream1(stream) {
+  foo()
+      . /// 01: compile-time error
+      .then();
+}
+
+void main() {
+  print(gotStream1);
+}