Handle detached table cells in autofill service (#10880)

Fixes errors and high CPU usage / browser lockup on offending webpages.

HTMLTableCellElement.cellIndex will be -1 if the cell is not part of any row, which will cause getTextContentFromElement to fail since it will not receive a valid sibling cell.

apps/browser/src/autofill/services/collect-autofill-content.service.ts

@@ -644,6 +644,10 @@ export class CollectAutofillContentService implements CollectAutofillContentServ
     }
 
     const tableDataElementIndex = tableDataElement.cellIndex;
+    if (tableDataElementIndex < 0) {
+      return null;
+    }
+
     const parentSiblingTableRowElement = tableDataElement.closest("tr")
       ?.previousElementSibling as HTMLTableRowElement;