AB3986 - Wrapped System.Web.Hosting.IRegisteredObject in the AspNetHostingEnvironment. Updated Maindom to use our own new interface and the wrapper and moved to infrastructure. Removed the Umbraco.Core project now that it was empty.

src/Umbraco.Tests/Testing/UmbracoTestBase.cs

@@ -354,7 +354,7 @@ namespace Umbraco.Tests.Testing
         {
             return new TypeLoader(ioHelper, typeFinder, runtimeCache, new DirectoryInfo(hostingEnvironment.LocalTempPath), logger, false, new[]
             {
-                Assembly.Load("Umbraco.Core"),
+                Assembly.Load("Umbraco.Abstractions"),
                 Assembly.Load("Umbraco.Web"),
                 Assembly.Load("Umbraco.Tests"),
                 Assembly.Load("Umbraco.Infrastructure")