Unity 使用Win32.RegistryKey的问题

在研究使用Microsoft.Speech.dll做语音命令词识别时，发现将该dll放到Unity工程中使用时会报如下错误：

NullReferenceException: Object reference not set to an instance of an object
Microsoft.Speech.Internal.ObjectTokens.RegistryDataKey.HKEYfromRegKey (Microsoft.Win32.RegistryKey regKey) (at <7c2225eddeb441b59b44afbea5394aaf>:0)
Microsoft.Speech.Internal.ObjectTokens.RegistryDataKey.RootHKEYFromRegPath (System.String rootPath) (at <7c2225eddeb441b59b44afbea5394aaf>:0)
Microsoft.Speech.Internal.ObjectTokens.RegistryDataKey.Open (System.String registryPath, System.Boolean fCreateIfNotExist) (at <7c2225eddeb441b59b44afbea5394aaf>:0)
Microsoft.Speech.Internal.ObjectTokens.ObjectTokenCategory.Create (System.String sCategoryId) (at <7c2225eddeb441b59b44afbea5394aaf>:0)
Microsoft.Speech.Recognition.SpeechRecognitionEngine.InstalledRecognizers () (at <7c2225eddeb441b59b44afbea5394aaf>:0)
Microsoft.Speech.Recognition.SpeechRecognitionEngine..ctor (System.Globalization.CultureInfo culture) (at <7c2225eddeb441b59b44afbea5394aaf>:0)

通过使用ILSpy查看过Microsoft.Speech.dll后发现，有这样的调用顺序：

1. Microsoft.Speech.Recognition.SpeechRecogintionEngine
2. foreach (RecognizerInfo item in InstalledRecognizers())
3. ObjectTokenCategory.Create("HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Speech Server\\v11.0\\Recognizers"))
4. RegistryDataKey.Open(sCategoryId, fCreateIfNotExist: true);
5. RootHKEYFromRegPath(firstKeyAndParseRemainder);
6. HKEYfromRegKey(registryKey);
7. private static IntPtr HKEYfromRegKey(RegistryKey regKey)
{
	Type typeFromHandle = typeof(RegistryKey);
	BindingFlags bindingAttr = BindingFlags.Instance | BindingFlags.NonPublic;
	FieldInfo field = typeFromHandle.GetField("hkey", bindingAttr);
	SafeHandle safeHandle = (SafeHandle)field.GetValue(regKey);
	return safeHandle.DangerousGetHandle();
}
8. 到这一步时，需要去查找RegistryKey类中通过反射找的私有变量hkey。
这个在.NET版本的mscorlib中，RegistryKey有如下变量：
private SafeRegistryHandle hkey;
而在Unity Editor的安装目录下mscorlib.dll中，是没有这个变量的。这样导致会抛异常。