Test that importing dart:core with a prefix does not hide dynamic.

tests/language/dynamic_prefix_core_test.dart

Index: tests/language/dynamic_prefix_core_test.dart
diff --git a/tests/language/dynamic_prefix_core_test.dart b/tests/language/dynamic_prefix_core_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..1aba87f3c789f95363328dbccfcf8179b3bcc5a0
--- /dev/null
+++ b/tests/language/dynamic_prefix_core_test.dart
@@ -0,0 +1,17 @@
+// Copyright (c) 2012, 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 explicit import of dart:core in the source code..
+
+library DynamicPrefixCoreTest.dart;
+import "package:expect/expect.dart";
+import "dart:core" as mycore;
+
+void main() {
+  // Should still be available because it is not a member of dart:core.
+  Expect.isTrue(dynamic is Type);
+  
+  Expect.throws(() => mycore.dynamic is Type,
+                (e) => e is NoSuchMethodError,
+                'dynamic is not a member of dart:core');
+}