Move generated files to gen/.

test/codegen/covariance.dart

Index: test/codegen/covariance.dart
diff --git a/test/codegen/covariance.dart b/test/codegen/covariance.dart
deleted file mode 100644
index 89c27615a523fedc6f4e536c89e221892b84b070..0000000000000000000000000000000000000000
--- a/test/codegen/covariance.dart
+++ /dev/null
@@ -1,27 +0,0 @@
-// 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.
-
-class Foo<T> {
-  T _t;
-  add(T t) {
-    _t = t;
-  }
-
-  forEach(void fn(T t)) {
-    // No check needed for `fn`
-    fn(_t);
-  }
-}
-
-class Bar extends Foo<int> {
-  add(int x) {
-    print('Bar.add got $x');
-    super.add(x);
-  }
-}
-
-main() {
-  Foo<Object> foo = new Bar();
-  foo.add('hi'); // should throw
-}