Revert "Access to imports in the VM's runtime mirrors. Extend test coverage of the source mirrors."

tests/lib/mirrors/library_imports_shown.dart

Index: tests/lib/mirrors/library_imports_shown.dart
diff --git a/tests/lib/mirrors/library_imports_shown.dart b/tests/lib/mirrors/library_imports_shown.dart
deleted file mode 100644
index 6790902e6953b560e6217a51d31154ac1fd25b2c..0000000000000000000000000000000000000000
--- a/tests/lib/mirrors/library_imports_shown.dart
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright (c) 2014, 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.
-
-library library_imports_shown;
-
-import 'library_imports_a.dart' show somethingFromA, somethingFromBoth;
-import 'library_imports_b.dart' show somethingFromB;
-
-var somethingFromShown;