Make private symbol mangling test work on the VM, as well.

tests/lib/mirrors/private_symbol_mangling_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 main;
 
 //@MirrorsUsed(targets: const ['C1', 'C2', '_privateGlobalField', '_privateGlobalMethod'])
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 import 'private_symbol_mangling_lib.dart';
 
 var _privateGlobalField = 1;
 
 _privateGlobalMethod() => 9;
 
 class C1 {
   var _privateField = 0;
   _privateMethod() => 2;
 }
 
 getPrivateGlobalFieldValue(LibraryMirror lib) {
   for (Symbol symbol in lib.declarations.keys) {
     DeclarationMirror decl = lib.declarations[symbol];
-    if (decl is VariableMirror) {
+    if (decl is VariableMirror && decl.isPrivate) {
       return lib.getField(symbol).reflectee;
     }
   }
 }
 
 getPrivateFieldValue(InstanceMirror cls) {
   for (Symbol symbol in cls.type.declarations.keys) {
     DeclarationMirror decl = cls.type.declarations[symbol];
-    if (decl is VariableMirror) {
+    if (decl is VariableMirror && decl.isPrivate) {
       return cls.getField(symbol).reflectee;
     }
   }
 }
 
 getPrivateGlobalMethodValue(LibraryMirror lib) {
   for (Symbol symbol in lib.declarations.keys) {
     DeclarationMirror decl = lib.declarations[symbol];
-    if (decl is MethodMirror && decl.isRegularMethod) {
+    if (decl is MethodMirror && decl.isRegularMethod && decl.isPrivate) {
       return lib.invoke(symbol, []).reflectee;
     }
   }
 }
 
 getPrivateMethodValue(InstanceMirror cls) {
   for (Symbol symbol in cls.type.declarations.keys) {
     DeclarationMirror decl = cls.type.declarations[symbol];
-    if (decl is MethodMirror && decl.isRegularMethod) {
+    if (decl is MethodMirror && decl.isRegularMethod && decl.isPrivate) {
       return cls.invoke(symbol, []).reflectee;
     }
   }
 }
 
 main() {
   LibraryMirror libmain = currentMirrorSystem().findLibrary(#main);
   LibraryMirror libother = currentMirrorSystem().findLibrary(#other);
   Expect.equals(1, getPrivateGlobalFieldValue(libmain));
   Expect.equals(3, getPrivateGlobalFieldValue(libother));
   Expect.equals(9, getPrivateGlobalMethodValue(libmain));
   Expect.equals(11, getPrivateGlobalMethodValue(libother));
 
   var c1 = reflect(new C1());
   var c2 = reflect(new C2());
   Expect.equals(0, getPrivateFieldValue(c1));
   Expect.equals(1, getPrivateFieldValue(c2));
   Expect.equals(2, getPrivateMethodValue(c1));
   Expect.equals(3, getPrivateMethodValue(c2));
 }