fixed assert where cshtml didn't get proper IVsHierarchy set

src/VisualStudio/Core/Def/Implementation/Venus/ContainedDocument.cs

@@ -72,12 +72,14 @@ internal sealed class ContainedDocument : ForegroundThreadAffinitizedObject, IVi
         private readonly string _itemMoniker;
 
         public AbstractProject Project { get { return _containedLanguage.Project; } }
-        public DocumentId Id { get; private set; }
-        public IReadOnlyList<string> Folders { get; private set; }
-        public TextLoader Loader { get; private set; }
-        public DocumentKey Key { get; private set; }
         public bool SupportsRename { get { return _hostType == HostType.Razor; } }
 
+        public DocumentId Id { get; }
+        public IReadOnlyList<string> Folders { get; }
+        public TextLoader Loader { get; }
+        public DocumentKey Key { get; }
+        public IVsHierarchy SharedHierarchy { get; }
+
         public ContainedDocument(
             AbstractContainedLanguage containedLanguage,
             SourceCodeKind sourceCodeKind,
@@ -99,6 +101,8 @@ internal sealed class ContainedDocument : ForegroundThreadAffinitizedObject, IVi
             var rdt = (IVsRunningDocumentTable)componentModel.GetService<SVsServiceProvider>().GetService(typeof(SVsRunningDocumentTable));
             var filePath = rdt.GetMonikerForHierarchyAndItemId(hierarchy, itemId);
 
+            this.SharedHierarchy = hierarchy == null ? null : LinkedFileUtilities.GetSharedHierarchyForItem(hierarchy, itemId);
+
             if (Project.Hierarchy != null)
             {
                 string moniker;
@@ -115,11 +119,6 @@ internal sealed class ContainedDocument : ForegroundThreadAffinitizedObject, IVi
             _vbHelperFormattingRule = vbHelperFormattingRule;
         }
 
-        public IVsHierarchy SharedHierarchy
-        {
-            get { return null; }
-        }
-
         private HostType GetHostType()
         {
             var projectionBuffer = _containedLanguage.DataBuffer as IProjectionBuffer;