Share addTypeVariableReference between factory calls and is-checks.

tests/compiler/dart2js_extra/typevariable_substitution_test.dart

Index: tests/compiler/dart2js_extra/typevariable_substitution_test.dart
diff --git a/tests/compiler/dart2js_extra/typevariable_substitution_test.dart b/tests/compiler/dart2js_extra/typevariable_substitution_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..8a40a8203a87561fc6c108798c73f3289e1ef345
--- /dev/null
+++ b/tests/compiler/dart2js_extra/typevariable_substitution_test.dart
@@ -0,0 +1,18 @@
+// Copyright (c) 2013, 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.
+
+// Regression test to ensure that we substitute type variables in is-tests.
+
+class A<T> {
+  A.foo(o) {
+    Expect.isTrue(o is A<T>);
+  }
+  A();
+}
+
+class B extends A<int> {
+  B.foo(o) : super.foo(o);
+}
+
+main() => new B.foo(new A<int>());