Move Rename implementation to new fully loaded document API.

src/EditorFeatures/Core.Wpf/InlineRename/CommandHandlers/RenameCommandHandler_RenameHandler.cs

@@ -49,13 +49,13 @@ public bool ExecuteCommand(RenameCommandArgs args, CommandExecutionContext conte
         {
             using (context.OperationContext.AddScope(allowCancellation: true, EditorFeaturesResources.Finding_token_to_rename))
             {
-                ExecuteRenameWorker(args, context.OperationContext.UserCancellationToken);
+                ExecuteRenameWorker(args, context);
             }
 
             return true;
         }
 
-        private void ExecuteRenameWorker(RenameCommandArgs args, CancellationToken cancellationToken)
+        private void ExecuteRenameWorker(RenameCommandArgs args, CommandExecutionContext context)
         {
             var snapshot = args.SubjectBuffer.CurrentSnapshot;
             if (!Workspace.TryGetWorkspace(snapshot.AsText().Container, out var workspace))
@@ -89,7 +89,9 @@ private void ExecuteRenameWorker(RenameCommandArgs args, CancellationToken cance
             }
 
             var position = caretPoint.Value;
-            var document = args.SubjectBuffer.CurrentSnapshot.GetOpenDocumentInCurrentContextWithChanges();
+            var cancellationToken = context.OperationContext.UserCancellationToken;
+            var document = args.SubjectBuffer.CurrentSnapshot.GetFullyLoadedOpenDocumentInCurrentContextWithChangesAsync(
+                context.OperationContext).WaitAndGetResult(cancellationToken);
             if (document == null)
             {
                 ShowErrorDialog(workspace, EditorFeaturesResources.You_must_rename_an_identifier);