Bug 1760734 - Put overflow: -moz-hidden-unscrollable behind a pref on Nightly. r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D141759

devtools/shared/css/generated/properties-db.js

@@ -9010,7 +9010,6 @@ exports.CSS_PROPERTIES = {
     ],
     "supports": [],
     "values": [
-      "-moz-hidden-unscrollable",
       "auto",
       "clip",
       "hidden",
@@ -9046,7 +9045,6 @@ exports.CSS_PROPERTIES = {
     ],
     "supports": [],
     "values": [
-      "-moz-hidden-unscrollable",
       "auto",
       "clip",
       "hidden",
@@ -9066,7 +9064,6 @@ exports.CSS_PROPERTIES = {
     ],
     "supports": [],
     "values": [
-      "-moz-hidden-unscrollable",
       "auto",
       "clip",
       "hidden",
@@ -9103,7 +9100,6 @@ exports.CSS_PROPERTIES = {
     ],
     "supports": [],
     "values": [
-      "-moz-hidden-unscrollable",
       "auto",
       "clip",
       "hidden",
@@ -9123,7 +9119,6 @@ exports.CSS_PROPERTIES = {
     ],
     "supports": [],
     "values": [
-      "-moz-hidden-unscrollable",
       "auto",
       "clip",
       "hidden",

layout/style/test/property_database.js

@@ -6815,14 +6815,12 @@ var gCSSProperties = {
       "auto",
       "scroll",
       "hidden",
-      "-moz-hidden-unscrollable",
       "clip",
       "auto auto",
       "auto scroll",
       "hidden scroll",
       "auto hidden",
       "clip clip",
-      "-moz-hidden-unscrollable -moz-hidden-unscrollable",
     ],
     invalid_values: [
       "clip -moz-scrollbars-none",
@@ -6842,13 +6840,7 @@ var gCSSProperties = {
       contain: "none",
     },
     initial_values: ["visible"],
-    other_values: [
-      "auto",
-      "scroll",
-      "hidden",
-      "clip",
-      "-moz-hidden-unscrollable",
-    ],
+    other_values: ["auto", "scroll", "hidden", "clip"],
     invalid_values: [],
   },
   "overflow-y": {
@@ -6862,13 +6854,7 @@ var gCSSProperties = {
       contain: "none",
     },
     initial_values: ["visible"],
-    other_values: [
-      "auto",
-      "scroll",
-      "hidden",
-      "clip",
-      "-moz-hidden-unscrollable",
-    ],
+    other_values: ["auto", "scroll", "hidden", "clip"],
     invalid_values: [],
   },
   "overflow-inline": {
@@ -6883,7 +6869,7 @@ var gCSSProperties = {
       contain: "none",
     },
     initial_values: ["visible"],
-    other_values: ["auto", "scroll", "hidden", "-moz-hidden-unscrollable"],
+    other_values: ["auto", "scroll", "hidden", "clip"],
     invalid_values: [],
   },
   "overflow-block": {
@@ -6898,7 +6884,7 @@ var gCSSProperties = {
       contain: "none",
     },
     initial_values: ["visible"],
-    other_values: ["auto", "scroll", "hidden", "-moz-hidden-unscrollable"],
+    other_values: ["auto", "scroll", "hidden", "clip"],
     invalid_values: [],
   },
   padding: {
@@ -11639,6 +11625,20 @@ if (IsCSSPropertyPrefEnabled("layout.css.caption-side-non-standard.enabled")) {
   );
 }
 
+{
+  const enabled = IsCSSPropertyPrefEnabled(
+    "layout.css.overflow-moz-hidden-unscrollable.enabled"
+  );
+  for (let p of ["overflow", "overflow-x", "overflow-y"]) {
+    let prop = gCSSProperties[p];
+    let values = enabled ? prop.other_values : prop.invalid_values;
+    values.push("-moz-hidden-unscrollable");
+    if (p == "overflow") {
+      values.push("-moz-hidden-unscrollable -moz-hidden-unscrollable");
+    }
+  }
+}
+
 if (IsCSSPropertyPrefEnabled("layout.css.individual-transform.enabled")) {
   gCSSProperties.rotate = {
     domProp: "rotate",

modules/libpref/init/StaticPrefList.yaml

@@ -7721,6 +7721,13 @@
   value: false
   mirror: always
 
+# Is support for CSS overflow: -moz-hidden-unscrollable enabled
+- name: layout.css.overflow-moz-hidden-unscrollable.enabled
+  type: RelaxedAtomicBool
+  value: @IS_NOT_NIGHTLY_BUILD@
+  mirror: always
+  rust: true
+
 # Is support for overscroll-behavior enabled?
 - name: layout.css.overscroll-behavior.enabled
   type: bool

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

@@ -2067,7 +2067,6 @@ impl BreakWithin {
     Eq,
     Hash,
     MallocSizeOf,
-    Parse,
     PartialEq,
     SpecifiedValueInfo,
     ToCss,
@@ -2082,10 +2081,28 @@ pub enum Overflow {
     Scroll,
     Auto,
     #[cfg(feature = "gecko")]
-    #[parse(aliases = "-moz-hidden-unscrollable")]
     Clip,
 }
 
+// This can be derived once we remove or keep `-moz-hidden-unscrollable`
+// indefinitely.
+impl Parse for Overflow {
+    fn parse<'i, 't>(_: &ParserContext, input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i>> {
+        Ok(try_match_ident_ignore_ascii_case! { input,
+            "visible" => Self::Visible,
+            "hidden" => Self::Hidden,
+            "scroll" => Self::Scroll,
+            "auto" => Self::Auto,
+            #[cfg(feature = "gecko")]
+            "clip" => Self::Clip,
+            #[cfg(feature = "gecko")]
+            "-moz-hidden-unscrollable" if static_prefs::pref!("layout.css.overflow-moz-hidden-unscrollable.enabled") => {
+               Overflow::Clip
+            },
+        })
+    }
+}
+
 impl Overflow {
     /// Return true if the value will create a scrollable box.
     #[inline]

testing/web-platform/tests/css/css-overflow/overflow-body-propagation-010.html

@@ -7,7 +7,6 @@
 <link rel="match" href="overflow-body-propagation-010-ref.html">
 <style>
   body {
-    overflow: -moz-hidden-unscrollable; /* will be removed in bug 1531609 */
     overflow: clip;
     contain: paint;
     width: 30px;