Re-triage mirror test failures on the analyzer.

tests/lib/mirrors/private_symbol_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;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 
 typedef int _F(int);
@@ skipping 91 matching lines @@
 
   TypeVariableMirror tvm = cm.typeVariables[0];
   Expect.isNotNull(tvm);
   Expect.equals(#_T, tvm.simpleName);
   Expect.equals('_T', MirrorSystem.getName(tvm.simpleName));
 
   TypedefMirror tdm = reflectType(_F);
   Expect.equals(#_F, tdm.simpleName);
   Expect.equals('_F', MirrorSystem.getName(tdm.simpleName));
 
-  ParameterMirror pm = cm.members[#m].parameters[0];
+  ParameterMirror pm = (cm.members[#m] as MethodMirror).parameters[0];
   Expect.equals(#_p, pm.simpleName);
   Expect.equals('_p', MirrorSystem.getName(pm.simpleName));
 
 
   // Private symbol without a library.
   Expect.throws(() => MirrorSystem.getSymbol('_private'),
                 (e) => e is ArgumentError);
 
   var notALibraryMirror = 7;
   Expect.throws(() => MirrorSystem.getSymbol('_private', notALibraryMirror),
                 (e) => e is ArgumentError || e is TypeError);
 
   Expect.throws(() => MirrorSystem.getSymbol('public', notALibraryMirror),
                 (e) => e is ArgumentError || e is TypeError);
 }