Don't create OptionKeys with language names if the option isn't per-language

src/VisualStudio/Core/Impl/Options/AbstractSettingsManagerOptionSerializer.cs

@@ -77,7 +77,7 @@ private Task OnSettingChangedAsync(object sender, PropertyChangedEventArgs args)
 
         private void SetChangedOption(IOptionService optionService, IOption option, string languageName)
         {
-            OptionKey key = new OptionKey(option, languageName);
+            OptionKey key = new OptionKey(option, option.IsPerLanguage ? languageName : null);
 
             object currentValue;
             if (this.TryFetch(key, out currentValue))