Fix deferred load errors / bug #26482

tests/standalone/deferred_transitive_import_error_test.dart

+// Copyright (c) 2016, 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 "package:expect/expect.dart";
+// A deferred library that doesn't exist.
+import 'package:foo/foo.dart' deferred as foo;
+// A deferred library that does exist.
+import 'deferred/exists.dart' deferred as exists;
+// A deferred library that transitively will fail due to a file not found.
+import 'deferred/transitive_error.dart' deferred as te;
+
+main() async {
+  // Attempt to load foo which will fail.
+  var fooError;
+  await foo.loadLibrary().catchError((e) {
+    fooError = e;
+  });
+  Expect.isNotNull(fooError);
+  await exists.loadLibrary();
+  Expect.equals(99, exists.x);
+  /* TODO(johnmccutchan): Implement transitive error reporting.
+  var teError;
+  await te.loadLibrary().catchError((e) {
+    teError = e;
+  });
+  Expect.isNotNull(teError);
+  */
+}