mshtml/tests: Fix test_tr_modify().

dlls/mshtml/tests/dom.c

@@ -5801,7 +5801,7 @@ static void test_tr_modify(IHTMLElement *elem, IHTMLTableRow *row)
 {
     HRESULT hres;
     IDispatch *disp;
-    IUnknown *unk;
+    IHTMLTableCell *cell;
 
     hres = IHTMLTableRow_deleteCell(row, 0);
     ok(hres == S_OK, "deleteCell failed: %08x\n", hres);
@@ -5810,10 +5810,11 @@ static void test_tr_modify(IHTMLElement *elem, IHTMLTableRow *row)
     hres = IHTMLTableRow_insertCell(row, 0, &disp);
     ok(hres == S_OK, "insertCell failed: %08x\n", hres);
     ok(disp != NULL, "disp == NULL\n");
-    hres = IDispatch_QueryInterface(disp, &IID_IHTMLTableCell, (void **)&unk);
+    hres = IDispatch_QueryInterface(disp, &IID_IHTMLTableCell, (void **)&cell);
     ok(hres == S_OK, "Could not get IID_IHTMLTableCell interface: %08x\n", hres);
+    ok(cell != NULL, "cell == NULL\n");
     if (SUCCEEDED(hres))
-        IUnknown_Release(unk);
+        IHTMLTableCell_Release(cell);
     test_tr_possess(elem, row, 2, "td2");
     IDispatch_Release(disp);
 }