Use the runtime for generic subsitution of variable types, return types, parameter types.

tests/lib/mirrors/generics_double_substitution_test.dart

+// 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.
+
+library test.generics_double_substitution;
+
+import 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class A<R> {}
+class B<S> {}
+class C<T> extends B<A<T>> {
+  A<T> field;
+  A<T> returnType() {}
+  parameterType(A<T> param) {}
+}
+
+main() {
+  ClassMirror cOfString = reflect(new C<String>()).type;
+  ClassMirror aOfString = reflect(new A<String>()).type;
+
+  VariableMirror field = cOfString.declarations[#field];
+  Expect.equals(aOfString, field.type);
+
+  MethodMirror returnType = cOfString.declarations[#returnType];
+  Expect.equals(aOfString, returnType.returnType);
+
+  MethodMirror parameterType = cOfString.declarations[#parameterType];
+  Expect.equals(aOfString, parameterType.parameters.single.type);
+
+  ClassMirror typeArgOfSuperclass = cOfString.superclass.typeArguments.single;
+  Expect.equals(aOfString, typeArgOfSuperclass);  /// 01: ok
+}