Add missing test coverage for constructor kinds, generic function typedefs and generic mixin applic…

tests/lib/mirrors/constructors_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.constructors_test;
 
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
 import 'stringify.dart';
 
 class Foo {
 }
 
 class Bar {
   Bar();
 }
 
 class Baz {
   Baz.named();
 }
 
 class Biz {
   Biz();
   Biz.named();
 }
 
 main() {
-  MirrorSystem mirrors = currentMirrorSystem();
   ClassMirror fooMirror = reflectClass(Foo);
   Map<Symbol, MethodMirror> fooConstructors = fooMirror.constructors;
   ClassMirror barMirror = reflectClass(Bar);
   Map<Symbol, MethodMirror> barConstructors = barMirror.constructors;
   ClassMirror bazMirror = reflectClass(Baz);
   Map<Symbol, MethodMirror> bazConstructors = bazMirror.constructors;
   ClassMirror bizMirror = reflectClass(Biz);
   Map<Symbol, MethodMirror> bizConstructors = bizMirror.constructors;
 
   expect('{Foo: Method(s(Foo) in s(Foo), constructor)}', fooConstructors);
@@ skipping 15 matching lines @@
   expect('[s()]',
          fooConstructors.values.map((m) => m.constructorName).toList());
   expect('[s()]',
          barConstructors.values.map((m) => m.constructorName).toList());
   expect('[s(named)]',
          bazConstructors.values.map((m) => m.constructorName).toList());
   expect('[s(), s(named)]',
          bizConstructors.values.map((m) => m.constructorName).toList()
              ..sort(compareSymbols));
 }