Auto merge of #17569 - upsuper:fullscreen, r=emilio

Support :-moz-full-screen pseudo-class

This fixes [bug 1374901](https://bugzilla.mozilla.org/show_bug.cgi?id=1374901).

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components/style/gecko/non_ts_pseudo_class_list.rs

@@ -66,6 +66,7 @@ macro_rules! apply_non_ts_list {
                 // TODO(emilio): Needs pref check for
                 // full-screen-api.unprefix.enabled!
                 ("fullscreen", Fullscreen, fullscreen, IN_FULLSCREEN_STATE, _),
+                ("-moz-full-screen", MozFullScreen, mozFullScreen, IN_FULLSCREEN_STATE, _),
                 // TODO(emilio): This is inconsistently named (the capital R).
                 ("-moz-focusring", MozFocusRing, mozFocusRing, IN_FOCUSRING_STATE, _),
                 ("-moz-broken", MozBroken, mozBroken, IN_BROKEN_STATE, _),

components/style/gecko/wrapper.rs

@@ -1657,6 +1657,7 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
             NonTSPseudoClass::Disabled |
             NonTSPseudoClass::Checked |
             NonTSPseudoClass::Fullscreen |
+            NonTSPseudoClass::MozFullScreen |
             NonTSPseudoClass::Indeterminate |
             NonTSPseudoClass::PlaceholderShown |
             NonTSPseudoClass::Target |