Move ITagHelperActivator DI registration.

- Moved the ITagHelperActivator registration in MvcServices to sit with the RazorPage pieces (it's used on the RazorPage).

src/Microsoft.AspNet.Mvc/MvcServices.cs

@@ -33,9 +33,6 @@ namespace Microsoft.AspNet.Mvc
 
             yield return describe.Transient<IOptionsAction<MvcOptions>, MvcOptionsSetup>();
 
-            // Only want one ITagHelperActivator so it can cache Type activation information. Types won't conflict.
-            yield return describe.Singleton<ITagHelperActivator, DefaultTagHelperActivator>();
-
             yield return describe.Transient<IControllerFactory, DefaultControllerFactory>();
             yield return describe.Singleton<IControllerActivator, DefaultControllerActivator>();
 
@@ -69,6 +66,9 @@ namespace Microsoft.AspNet.Mvc
             // Caches view locations that are valid for the lifetime of the application.
             yield return describe.Singleton<IViewLocationCache, DefaultViewLocationCache>();
 
+            // Only want one ITagHelperActivator so it can cache Type activation information. Types won't conflict.
+            yield return describe.Singleton<ITagHelperActivator, DefaultTagHelperActivator>();
+
             yield return describe.Singleton<IRazorPageActivator, RazorPageActivator>();
             // Virtual path view factory needs to stay scoped so views can get get scoped services.
             yield return describe.Scoped<IRazorPageFactory, VirtualPathRazorPageFactory>();