Add WPT test for getAttributeType() with qualified attribute name.

See w3c/trusted-types#496 (comment)

Differential Revision: https://phabricator.services.mozilla.com/D226476

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1917783
gecko-commit: aba2bd9d817f21ac8a590235dc6635861aea19eb
gecko-reviewers: smaug

Author: fred-wang

trusted-types/TrustedTypePolicyFactory-getPropertyType.tentative.html

@@ -134,5 +134,10 @@
     assert_equals(trustedTypes.getAttributeType("script", "href", NSURI_SVG.toUpperCase(), NSURI_XLINK), null, "case-sensitiveness of elementNs");
     assert_equals(trustedTypes.getAttributeType("script", "href", NSURI_SVG, NSURI_XLINK.toUpperCase()), null, "case-sensitiveness of attrNs");
   }, "getAttributeType with explicit elementNs and attrNs parameters");
+
+  test(t => {
+    assert_equals(trustedTypes.getAttributeType("script", "href", NSURI_SVG, NSURI_XLINK), "TrustedScriptURL", "local name 'href'");
+    assert_equals(trustedTypes.getAttributeType("script", "xlink:href", NSURI_SVG, NSURI_XLINK), null, "qualified name 'xlink:href'");
+  }, "getAttributeType with qualified attribute name");
 </script>
 </body>