turn on the pref for text-decoration-thickness on by default (in earl…

…y-beta and earlier)

Differential Revision: https://phabricator.services.mozilla.com/D41883

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1573725
gecko-commit: 27209bcee14fe4bdbfb87c1f128035b3d1cb7f96
gecko-integration-branch: autoland
gecko-reviewers: dholbert

css/css-text-decor/parsing/text-decoration-invalid.html

@@ -7,9 +7,6 @@
 <script src="/resources/testharnessreport.js"></script>
 <script src="/css/support/parsing-testcommon.js"></script>
 <script>
-test_invalid_value("text-decoration", "auto");
-test_invalid_value("text-decoration", "1px");
-
 test_invalid_value("text-decoration", "double overline underline dotted");
 test_invalid_value("text-decoration", "red line-through green");
 test_invalid_value("text-decoration", "overline blue underline");