style: Unprefix -moz-read-write / -moz-read-only.

And remove some duplicated tests from WPT.

Differential Revision: https://phabricator.services.mozilla.com/D75231

components/style/gecko/selector_parser.rs

@@ -119,6 +119,8 @@ impl NonTSPseudoClass {
                 match_ignore_ascii_case! { &name,
                     $($css => Some(NonTSPseudoClass::$name),)*
                     "-moz-full-screen" => Some(NonTSPseudoClass::Fullscreen),
+                    "-moz-read-only" => Some(NonTSPseudoClass::ReadOnly),
+                    "-moz-read-write" => Some(NonTSPseudoClass::ReadWrite),
                     _ => None,
                 }
             }