Bug 1789790: When a row is added to a table, push a cache update for the table's layout guess. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D156810

accessible/generic/LocalAccessible.cpp

@@ -2494,6 +2494,12 @@ void LocalAccessible::BindToParent(LocalAccessible* aParent,
         table->GetHeaderCache().Clear();
       }
     }
+  } else if (IsTableRow() && aParent->IsTable() &&
+             StaticPrefs::accessibility_cache_enabled_AtStartup()) {
+    // This table might have previously been treated as a layout table. Now that
+    // a row has been added, it might have sufficient rows to be considered a
+    // data table.
+    mDoc->QueueCacheUpdate(aParent, CacheDomain::Table);
   }
 
 #if defined(XP_WIN)