Bug 1600998 - Remove layout.css.xul-box-display-values.survive-blockification.enabled. r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D55898

--HG--
extra : moz-landing-system : lando

layout/reftests/box/reftest.list

@@ -1,4 +1,4 @@
-test-pref(layout.css.xul-box-display-values.content.enabled,true) test-pref(layout.css.xul-box-display-values.survive-blockification.enabled,true) == box-as-grid-or-flex-item-1.html box-as-grid-or-flex-item-1-ref.html
+test-pref(layout.css.xul-box-display-values.content.enabled,true) == box-as-grid-or-flex-item-1.html box-as-grid-or-flex-item-1-ref.html
 
 == flexbox-abspos-container-1a.html flexbox-abspos-container-1-ref.html
 == flexbox-abspos-container-1b.html flexbox-abspos-container-1-ref.html

layout/xul/test/test_blockify_moz_box.html

@@ -117,7 +117,6 @@ function runTest() {
 SpecialPowers.pushPrefEnv({
   "set": [
     ["layout.css.xul-box-display-values.content.enabled", true],
-    ["layout.css.xul-box-display-values.survive-blockification.enabled", true]
   ]
 }, runTest);
 

modules/libpref/init/StaticPrefList.yaml

@@ -5241,14 +5241,6 @@
   mirror: always
   rust: true
 
-# Pref to control whether display: -moz-box and display: -moz-inline-box are
-# "blockified" to "-moz-box" (rather than to "block")
-- name: layout.css.xul-box-display-values.survive-blockification.enabled
-  type: RelaxedAtomicBool
-  value: true
-  mirror: always
-  rust: true
-
 # Pref to control whether XUL ::-tree-* pseudo-elements are parsed in content
 # pages.
 - name: layout.css.xul-tree-pseudos.content.enabled

servo/components/style/values/specified/box.rs

@@ -389,20 +389,11 @@ impl Display {
                 };
                 Display::from3(DisplayOutside::Block, inside, self.is_list_item())
             },
-            // If this pref is true, then we'll blockify "-moz-inline-box" to
-            // "-moz-box", and blockify "-moz-box" to itself. Otherwise, we
-            // blockify both to "block".
             #[cfg(feature = "gecko")]
             DisplayOutside::XUL => {
-                if static_prefs::pref!(
-                    "layout.css.xul-box-display-values.survive-blockification.enabled"
-                ) {
-                    match self.inside() {
-                        DisplayInside::MozInlineBox | DisplayInside::MozBox => Display::MozBox,
-                        _ => Display::Block,
-                    }
-                } else {
-                    Display::Block
+                match self.inside() {
+                    DisplayInside::MozInlineBox | DisplayInside::MozBox => Display::MozBox,
+                    _ => Display::Block,
                 }
             },
             DisplayOutside::Block | DisplayOutside::None => *self,