Update the prefers-contrast media query to use the new more/less keywords

Per the resolution here:
w3c/csswg-drafts#2943 (comment)

Differential Revision: https://phabricator.services.mozilla.com/D86848

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1658780
gecko-commit: f700072e4306e5c87fcc84752fcad59fe8f13d52
gecko-integration-branch: autoland
gecko-reviewers: emilio

Author: 0xekez

css/mediaqueries/prefers-contrast.html

@@ -7,8 +7,8 @@
 <script>
 query_should_be_css_parseable("(prefers-contrast)");
 query_should_be_css_parseable("(prefers-contrast: no-preference)");
-query_should_be_css_parseable("(prefers-contrast: high)");
-query_should_be_css_parseable("(prefers-contrast: low)");
+query_should_be_css_parseable("(prefers-contrast: more)");
+query_should_be_css_parseable("(prefers-contrast: less)");
 query_should_be_css_parseable("(prefers-contrast: forced)");
 
 query_should_not_be_css_parseable("(prefers-contrast: increase)");
@@ -18,11 +18,13 @@
 query_should_not_be_css_parseable("(prefers-contrast > increase)");
 query_should_not_be_css_parseable("(prefers-increased-contrast)");
 query_should_not_be_css_parseable("(prefers-decreased-contrast)");
+query_should_not_be_css_parseable("(prefers-contrast: high)");
+query_should_not_be_css_parseable("(prefers-contrast: low)");
 
 query_should_be_js_parseable("(prefers-contrast)");
 query_should_be_js_parseable("(prefers-contrast: no-preference)");
-query_should_be_js_parseable("(prefers-contrast: high)");
-query_should_be_js_parseable("(prefers-contrast: low)");
+query_should_be_js_parseable("(prefers-contrast: more)");
+query_should_be_js_parseable("(prefers-contrast: less)");
 query_should_be_js_parseable("(prefers-contrast: forced)");
 
 query_should_not_be_js_parseable("(prefers-contrast: increase)");
@@ -32,6 +34,8 @@
 query_should_not_be_js_parseable("(prefers-contrast > increase)");
 query_should_not_be_js_parseable("(prefers-increased-contrast)");
 query_should_not_be_js_parseable("(prefers-decreased-contrast)");
+query_should_not_be_js_parseable("(prefers-contrast: high)");
+query_should_not_be_js_parseable("(prefers-contrast: low)");
 
 test(() => {
   // no-preference is the default and all other values evaluate to