Imported Upstream version 5.0.0.48

Former-commit-id: 820b1abb8b0084602f3170cd587a99c905e1dae5

external/binary-reference-assemblies/src/v4.5/System.Web.extra.cs

@@ -0,0 +1,13 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System.Web.UI.WebControls
+{
+    [System.Web.UI.ControlBuilderAttribute(typeof(ContentBuilderInternal))]
+    partial class Content { }
+    [System.Web.UI.ControlBuilder(typeof(ContentPlaceHolderBuilder))]
+    partial class ContentPlaceHolder { }
+    internal partial class ContentBuilderInternal { }
+    internal partial class ContentPlaceHolderBuilder { }
+}