Remove unnecessary ToLowerInvariant call from PreviewMode

Text was being set lowercase and then injected with the preview badge markup. This meant that things such as script tags were being lowercased, breaking the javascript.

src/Umbraco.Web/Mvc/UmbracoViewPageOfTModel.cs

@@ -238,7 +238,7 @@ namespace Umbraco.Web.Mvc
             {
                 if (UmbracoContext.Current.IsDebug || UmbracoContext.Current.InPreviewMode)
                 {
-                    var text = value.ToString().ToLowerInvariant();
+                    var text = value.ToString();
                     var pos = text.IndexOf("</body>", StringComparison.InvariantCultureIgnoreCase);
 
                     if (pos > -1)
@@ -294,4 +294,4 @@ namespace Umbraco.Web.Mvc
             return WebViewPageExtensions.RenderSection(this, name, defaultContents);
         }
     }
-}
+}