Small fix for notebook search

Author: osortega

src/vs/workbench/contrib/search/browser/notebookSearch/notebookSearchModelBase.ts

@@ -44,7 +44,6 @@ export function isIMatchInNotebook(obj: any): obj is IMatchInNotebook {
 		typeof obj.parent === 'function' &&
 		typeof obj.cellParent === 'object' &&
 		typeof obj.isWebviewMatch === 'function' &&
-		typeof obj.isReadonly === 'function' &&
 		typeof obj.cellIndex === 'number' &&
 		(typeof obj.webviewIndex === 'number' || obj.webviewIndex === undefined) &&
 		(typeof obj.cell === 'object' || obj.cell === undefined);