style: Evaluate size feature to unknown if the container lacks size containment

For example, inline elements may have container-type:size but they don't
support size containment, so @container(width >= 0) shouldn't match.

Differential Revision: https://phabricator.services.mozilla.com/D163936

components/style/dom.rs

@@ -943,8 +943,10 @@ pub trait TElement:
     fn namespace(&self)
         -> &<SelectorImpl as selectors::parser::SelectorImpl>::BorrowedNamespaceUrl;
 
-    /// Returns the size of the primary box of the element.
+    /// Returns the size of the element to be used in container size queries.
-    fn primary_content_box_size(&self) -> euclid::default::Size2D<Option<app_units::Au>>;
+    /// This will usually be the size of the content area of the primary box,
+    /// but can be None if there is no box or if some axis lacks size containment.
+    fn query_container_size(&self) -> euclid::default::Size2D<Option<app_units::Au>>;
 }
 
 /// TNode and TElement aren't Send because we want to be careful and explicit

components/style/gecko/wrapper.rs

@@ -322,11 +322,6 @@ impl<'ln> GeckoNode<'ln> {
         self.flags() & (NODE_IS_IN_SHADOW_TREE as u32) != 0
     }
 
-    #[inline]
-    fn is_connected(&self) -> bool {
-        self.get_bool_flag(nsINode_BooleanFlag::IsConnected)
-    }
-
     /// WARNING: This logic is duplicated in Gecko's FlattenedTreeParentIsParent.
     /// Make sure to mirror any modifications in both places.
     #[inline]
@@ -1041,29 +1036,16 @@ impl<'le> TElement for GeckoElement<'le> {
     }
 
     #[inline]
-    fn primary_content_box_size(&self) -> Size2D<Option<Au>> {
+    fn query_container_size(&self) -> Size2D<Option<Au>> {
-        if !self.as_node().is_connected() {
+        let mut width = -1;
-            return Size2D::new(None, None)
+        let mut height = -1;
-        }
-
         unsafe {
-            let frame = self
+            bindings::Gecko_GetQueryContainerSize(self.0, &mut width, &mut height);
-                .0
-                ._base
-                ._base
-                ._base
-                .__bindgen_anon_1
-                .mPrimaryFrame
-                .as_ref();
-            if frame.is_null() {
-                return Size2D::new(None, None)
-            }
-            let mut width = 0;
-            let mut height = 0;
-            bindings::Gecko_ContentSize(*frame, &mut width, &mut height);
-            // FIXME: Should use None if there isn't size containment.
-            Size2D::new(Some(Au(width)), Some(Au(height)))
         }
+        Size2D::new(
+            if width >= 0 { Some(Au(width)) } else { None },
+            if height >= 0 { Some(Au(height)) } else { None },
+        )
     }
 
     /// Return the list of slotted nodes of this node.

components/style/stylesheets/container_rule.rs

@@ -201,7 +201,7 @@ impl ContainerCondition {
             }
         }
 
-        let size = potential_container.primary_content_box_size();
+        let size = potential_container.query_container_size();
         let style = style.clone();
         TraversalResult::Done(ContainerLookupResult {
             element: potential_container,
@@ -464,7 +464,7 @@ impl<'a> ContainerSizeQuery<'a> {
         let box_style = style.get_box();
 
         let container_type = box_style.clone_container_type();
-        let size = e.primary_content_box_size();
+        let size = e.query_container_size();
         match container_type {
             ContainerType::Size => {
                 TraversalResult::Done(