Handle creating ParameterMirrors for the parameters of forwarding constructors.

tests/lib/mirrors/parameter_of_mixin_app_constructor_test.dart

+// 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 test.parameter_of_mixin_app_constructor;
+
+import 'dart:mirrors';
+import 'stringify.dart';
+
+class MapView {
+  final _map;
+  MapView(map) : this._map = map;
+}
+
+abstract class UnmodifiableMapMixin {
+  someFunctionality() {}
+}
+
+class UnmodifiableMapView1 extends MapView with UnmodifiableMapMixin {
+  UnmodifiableMapView1(map1) : super(map1);  
+}
+
+class UnmodifiableMapView2 = MapView with UnmodifiableMapMixin;
+
+expectParameters(MethodMirror mm, List parameterNames) {
+  Expect.listEquals(mm, )
+}
+
+soleConstructorOf(ClassMirror cm) {
+  return cm.declarations.values
+      .where((dm) => dm is MethodMirror && dm.isConstructor).single;
+}
+
+main() {
+  ClassMirror umv1 = reflectClass(UnmodifiableMapView1);
+  expect('[Parameter(s(map1) in s(UnmodifiableMapView1),'
+         ' type = Type(s(dynamic), top-level))]',
+         soleConstructorOf(umv1).parameters);
+  expect('[Parameter(s(map) in s(test.parameter_of_mixin_app_constructor.MapView'
+         ' with test.parameter_of_mixin_app_constructor.UnmodifiableMapMixin),'
+         ' type = Type(s(dynamic), top-level))]',
+         soleConstructorOf(umv1.superclass).parameters);
+  expect('[Parameter(s(map) in s(MapView),'
+         ' type = Type(s(dynamic), top-level))]',
+         soleConstructorOf(umv1.superclass.superclass).parameters);
+  expect('[]',
+         soleConstructorOf(umv1.superclass.superclass.superclass).parameters);
+
+  ClassMirror umv2 = reflectClass(UnmodifiableMapView2);
+  expect('[Parameter(s(map) in s(UnmodifiableMapView2),'
+         ' type = Type(s(dynamic), top-level))]',
+         soleConstructorOf(umv2).parameters);
+  expect('[Parameter(s(map) in s(MapView),'
+         ' type = Type(s(dynamic), top-level))]',
+         soleConstructorOf(umv2.superclass).parameters);
+  expect('[]',
+         soleConstructorOf(umv2.superclass.superclass).parameters);
+}