Move GlobalizationMode initialization into a nested class (#53082)

Author: marek-safar

src/libraries/System.Private.CoreLib/src/System/Globalization/CultureData.cs

@@ -673,8 +673,9 @@ private static CultureData CreateCultureWithInvariantData()
                 return CultureData.Invariant;
             }
 
-            if (GlobalizationMode.PredefinedCulturesOnly && !GlobalizationMode.Invariant)
+            if (GlobalizationMode.PredefinedCulturesOnly)
             {
+                Debug.Assert(!GlobalizationMode.Invariant);
                 if (GlobalizationMode.UseNls ? !NlsIsEnsurePredefinedLocaleName(cultureName): !IcuIsEnsurePredefinedLocaleName(cultureName))
                     return null;
             }

src/libraries/System.Private.CoreLib/src/System/Globalization/GlobalizationMode.Unix.cs

@@ -5,9 +5,12 @@ namespace System.Globalization
 {
     internal static partial class GlobalizationMode
     {
-        // Order of these properties in Windows matter because GetUseIcuMode is dependent on Invariant.
-        // So we need Invariant to be initialized first.
-        internal static bool Invariant { get; } = GetGlobalizationInvariantMode();
+        private static partial class Settings
+        {
+            internal static readonly bool Invariant = GetGlobalizationInvariantMode();
+        }
+
+        internal static bool Invariant => Settings.Invariant;
 
         internal static bool UseNls => false;
 

src/libraries/System.Private.CoreLib/src/System/Globalization/GlobalizationMode.cs

@@ -8,15 +8,19 @@ namespace System.Globalization
 {
     internal static partial class GlobalizationMode
     {
+        private static partial class Settings
+        {
+            internal static readonly bool PredefinedCulturesOnly = AppContextConfigHelper.GetBooleanConfig("System.Globalization.PredefinedCulturesOnly", "DOTNET_SYSTEM_GLOBALIZATION_PREDEFINED_CULTURES_ONLY");
+        }
+
+        internal static bool PredefinedCulturesOnly => !Invariant && Settings.PredefinedCulturesOnly;
+
         private static bool GetInvariantSwitchValue() =>
             AppContextConfigHelper.GetBooleanConfig("System.Globalization.Invariant", "DOTNET_SYSTEM_GLOBALIZATION_INVARIANT");
 
         private static bool TryGetAppLocalIcuSwitchValue([NotNullWhen(true)] out string? value) =>
             TryGetStringValue("System.Globalization.AppLocalIcu", "DOTNET_SYSTEM_GLOBALIZATION_APPLOCALICU", out value);
 
-        internal static bool PredefinedCulturesOnly { get; } =
-            AppContextConfigHelper.GetBooleanConfig("System.Globalization.PredefinedCulturesOnly", "DOTNET_SYSTEM_GLOBALIZATION_PREDEFINED_CULTURES_ONLY");
-
         private static bool TryGetStringValue(string switchName, string envVariable, [NotNullWhen(true)] out string? value)
         {
             value = AppContext.GetData(switchName) as string;