Fix grid-area-valid.html test to not accept serialization results tha…

…t are clearly invalid.

w3c/csswg-drafts#2858

Differential Revision: https://phabricator.services.mozilla.com/D54417

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1598932
gecko-commit: fec93f8968c976eb4c84f2bcd62df2a95e004a75
gecko-integration-branch: autoland
gecko-reviewers: emilio

css/css-grid/parsing/grid-area-valid.html

@@ -76,11 +76,12 @@
 test_valid_value("grid-row", "1 / auto", "1");
 test_valid_value("grid-column", "2 j / span 3 k");
 
-
 // https://github.com/w3c/csswg-drafts/issues/2858
-// '\\31 st' in Blink, Firefox, '1st' in Edge, '"1st"' in Safari.
-test_valid_value("grid-column-end",  "\\31st", ["\\31 st", "1st", '"1st"']);
-test_valid_value("grid-column-end",  "\\31 st", ["\\31 st", "1st", '"1st"']);
+// '\\31 st' in Blink, Firefox, EdgeHTML and Safari serialize invalid values.
+test_valid_value("grid-column-end", "\\31st", ["\\31 st", "\\31st"]);
+test_valid_value("grid-column-end", "\\31 st", ["\\31 st", "\\31st"]);
+test_valid_value("grid-column", "\\31st / \\31 st", ["\\31 st", "\\31st"]);
+
 </script>
 </body>
 </html>