Support `::part` selector (#37307)

This is pretty much just wiring up the necessary stylo methods. Note
that the `exportparts` attribute is not yet supported, I'll do that in a
followup change

Testing: Covered by existing web platform tests.
This is the first half of https://github.com/servo/servo/issues/35349

Fixes https://github.com/servo/servo/issues/37325

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

1 files changed, 8 insertions, 1 deletions

diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index bf36242572f..6d4a0d2529e 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -1583,6 +1583,7 @@ pub(crate) unsafe fn from_untrusted_node_address(candidate: UntrustedNodeAddress
 pub(crate) trait LayoutNodeHelpers<'dom> {
     fn type_id_for_layout(self) -> NodeTypeId;
 
+    fn parent_node_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn first_child_ref(self) -> Option<LayoutDom<'dom, Node>>;
     fn last_child_ref(self) -> Option<LayoutDom<'dom, Node>>;
@@ -1645,7 +1646,7 @@ pub(crate) trait LayoutNodeHelpers<'dom> {
 impl<'dom> LayoutDom<'dom, Node> {
     #[inline]
     #[allow(unsafe_code)]
-    fn parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
+    pub(crate) fn parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
         unsafe { self.unsafe_get().parent_node.get_inner_as_layout() }
     }
 }
@@ -1662,6 +1663,12 @@ impl<'dom> LayoutNodeHelpers<'dom> for LayoutDom<'dom, Node> {
     }
 
     #[inline]
+    #[allow(unsafe_code)]
+    fn parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
+        unsafe { self.unsafe_get().parent_node.get_inner_as_layout() }
+    }
+
+    #[inline]
     fn composed_parent_node_ref(self) -> Option<LayoutDom<'dom, Node>> {
         let parent = self.parent_node_ref();
         if let Some(parent) = parent {