Revert #19666 since we do create NAC elements and expect them to be inline.

This reverts commit 1970e82b0d, reversing
changes made to e882660ea6.

The reparenting logic is still bogus, but I'll figure out how to deal with that
in a bit.

components/layout_thread/dom_wrapper.rs

@@ -460,6 +460,10 @@ impl<'le> TElement for ServoLayoutElement<'le> {
         }
     }
 
+    fn skip_root_and_item_based_display_fixup(&self) -> bool {
+        false
+    }
+
     unsafe fn set_selector_flags(&self, flags: ElementSelectorFlags) {
         self.element.insert_selector_flags(flags);
     }

components/style/dom.rs

@@ -670,6 +670,11 @@ pub trait TElement
         self.get_data().map(|x| x.borrow_mut())
     }
 
+    /// Whether we should skip any root- or item-based display property
+    /// blockification on this element.  (This function exists so that Gecko
+    /// native anonymous content can opt out of this style fixup.)
+    fn skip_root_and_item_based_display_fixup(&self) -> bool;
+
     /// Sets selector flags, which indicate what kinds of selectors may have
     /// matched on this element and therefore what kind of work may need to
     /// be performed when DOM state changes.

components/style/gecko/wrapper.rs

@@ -1256,6 +1256,19 @@ impl<'le> TElement for GeckoElement<'le> {
         }
     }
 
+    #[inline]
+    fn skip_root_and_item_based_display_fixup(&self) -> bool {
+        if !self.is_native_anonymous() {
+            return false;
+        }
+
+        if let Some(p) = self.implemented_pseudo_element() {
+            return p.skip_item_based_display_fixup();
+        }
+
+        self.is_root_of_native_anonymous_subtree()
+    }
+
     unsafe fn set_selector_flags(&self, flags: ElementSelectorFlags) {
         debug_assert!(!flags.is_empty());
         self.set_flags(selector_flags_to_node_flags(flags));

components/style/properties/properties.mako.rs

@@ -3060,10 +3060,14 @@ bitflags! {
     pub struct CascadeFlags: u8 {
         /// Whether to inherit all styles from the parent. If this flag is not
         /// present, non-inherited styles are reset to their initial values.
-        const INHERIT_ALL = 1 << 0;
+        const INHERIT_ALL = 1;
+
+        /// Whether to skip any display style fixup for root element, flex/grid
+        /// item, and ruby descendants.
+        const SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP = 1 << 1;
 
         /// Whether to only cascade properties that are visited dependent.
-        const VISITED_DEPENDENT_ONLY = 1 << 1;
+        const VISITED_DEPENDENT_ONLY = 1 << 2;
 
         /// Whether the given element we're styling is the document element,
         /// that is, matches :root.
@@ -3073,15 +3077,15 @@ bitflags! {
         ///
         /// This affects some style adjustments, like blockification, and means
         /// that it may affect global state, like the Device's root font-size.
-        const IS_ROOT_ELEMENT = 1 << 2;
+        const IS_ROOT_ELEMENT = 1 << 3;
 
         /// Whether we're computing the style of a link, either visited or
         /// unvisited.
-        const IS_LINK = 1 << 3;
+        const IS_LINK = 1 << 4;
 
         /// Whether we're computing the style of a link element that happens to
         /// be visited.
-        const IS_VISITED_LINK = 1 << 4;
+        const IS_VISITED_LINK = 1 << 5;
     }
 }
 

components/style/style_adjuster.rs

@@ -28,12 +28,6 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         StyleAdjuster { style }
     }
 
-    /// Whether to skip any display style fixup flex/grid item, and ruby
-    /// descendants.
-    fn skip_item_based_display_fixup(&self) -> bool {
-        self.style.pseudo.as_ref().map_or(false, |p| p.skip_item_based_display_fixup())
-    }
-
     /// <https://fullscreen.spec.whatwg.org/#new-stacking-layer>
     ///
     ///    Any position value other than 'absolute' and 'fixed' are
@@ -72,11 +66,10 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
             }
         }
 
-        blockify_if!(flags.contains(CascadeFlags::IS_ROOT_ELEMENT));
+        if !flags.contains(CascadeFlags::SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP) {
-        blockify_if!(
+            blockify_if!(flags.contains(CascadeFlags::IS_ROOT_ELEMENT));
-            !self.skip_item_based_display_fixup() &&
+            blockify_if!(layout_parent_style.get_box().clone_display().is_item_container());
-            layout_parent_style.get_box().clone_display().is_item_container()
+        }
-        );
 
         let is_item_or_root = blockify;
 
@@ -454,7 +447,9 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
     fn adjust_for_ruby(
         &mut self,
         layout_parent_style: &ComputedValues,
+        flags: CascadeFlags,
     ) {
+        use properties::CascadeFlags;
         use properties::computed_value_flags::ComputedValueFlags;
         use properties::longhands::unicode_bidi::computed_value::T as UnicodeBidi;
 
@@ -463,7 +458,7 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         if self.should_suppress_linebreak(layout_parent_style) {
             self.style.flags.insert(ComputedValueFlags::SHOULD_SUPPRESS_LINEBREAK);
             // Inlinify the display type if allowed.
-            if !self.skip_item_based_display_fixup() {
+            if !flags.contains(CascadeFlags::SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP) {
                 let inline_display = self_display.inlinify();
                 if self_display != inline_display {
                     self.style.mutate_box().set_display(inline_display);
@@ -599,7 +594,7 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         self.adjust_for_text_decoration_lines(layout_parent_style);
         #[cfg(feature = "gecko")]
         {
-            self.adjust_for_ruby(layout_parent_style);
+            self.adjust_for_ruby(layout_parent_style, flags);
         }
         self.set_bits();
     }

components/style/style_resolver.rs

@@ -542,6 +542,11 @@ where
 
         let mut cascade_flags = CascadeFlags::empty();
 
+        if self.element.skip_root_and_item_based_display_fixup() ||
+           pseudo.map_or(false, |p| p.skip_item_based_display_fixup()) {
+            cascade_flags.insert(CascadeFlags::SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP);
+        }
+
         if pseudo.is_none() && self.element.is_link() {
             cascade_flags.insert(CascadeFlags::IS_LINK);
             if self.element.is_visited_link() &&

ports/geckolib/glue.rs

@@ -2019,11 +2019,12 @@ pub extern "C" fn Servo_ComputedValues_GetForAnonymousBox(parent_style_or_null:
         page_decls,
     );
 
+    let cascade_flags = CascadeFlags::SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP;
     data.stylist.precomputed_values_for_pseudo_with_rule_node(
         &guards,
         &pseudo,
         parent_style_or_null.map(|x| &*x),
-        CascadeFlags::empty(),
+        cascade_flags,
         &metrics,
         rule_node
     ).into()
@@ -3619,17 +3620,10 @@ pub extern "C" fn Servo_ReparentStyle(
     let element = element.map(GeckoElement);
 
     let mut cascade_flags = CascadeFlags::empty();
+    if style_to_reparent.is_anon_box() {
+        cascade_flags.insert(CascadeFlags::SKIP_ROOT_AND_ITEM_BASED_DISPLAY_FIXUP);
+    }
     if let Some(element) = element {
-        // NOTE(emilio): This relies on element.is_some() => pseudo.is_none(),
-        // which the caller guarantees, fortunately. But this doesn't handle the
-        // IS_ROOT_ELEMENT flag correctly!
-        //
-        // I think it's not possible to wrap a root element in a first-line
-        // frame (and reparenting only happens for ::first-line and its
-        // descendants), so this may be fine...
-        //
-        // We should just get rid of all these flags which pass element / pseudo
-        // state.
         if element.is_link() {
             cascade_flags.insert(CascadeFlags::IS_LINK);
             if element.is_visited_link() && doc_data.visited_styles_enabled() {