Reducing duplication of Environment variable extraction

src/System.Management.Automation/security/SecuritySupport.cs

@@ -211,6 +211,7 @@ namespace System.Management.Automation.Internal
         private static void CleanKeyParents(RegistryKey baseKey, string keyPath)
         {
 #if CORECLR
+            // if ( ! Platform.Inbox) // Modify this to support registry checks for inbox CoreCLR
             return;
 #else // Windows && FullCLR
             using (RegistryKey key = baseKey.OpenSubKey(keyPath, true))