Avoid a few more allocations in another DocumentState path.

src/Workspaces/Core/Portable/Workspace/Solution/DocumentState.cs

@@ -363,7 +363,12 @@ public new DocumentState UpdateText(TextLoader loader, PreservationMode mode)
                 ? CreateStrongText(loader, this.Id, this.solutionServices, reportInvalidDataException: true)
                 : CreateRecoverableText(loader, this.Id, this.solutionServices, reportInvalidDataException: true);
 
-            var newTreeSource = CreateLazyFullyParsedTree(
+            // Only create the ValueSource for creating the SyntaxTree if this is a Document that
+            // supports SyntaxTrees.  There's no point in creating the async lazy and holding onto
+            // this data otherwise.
+            var newTreeSource = !this.SupportsSyntaxTree
+                ? ValueSource<TreeAndVersion>.Empty
+                : CreateLazyFullyParsedTree(
                     newTextSource,
                     this.Id.ProjectId,
                     GetSyntaxTreeFilePath(this.info),