From ccf8a436490992d01ad4bd99e79a2b4e2e649361 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Jim=C3=A9nez=20Moreno?= <ferjmoreno@gmail.com>
Date: Mon, 4 Mar 2019 14:22:52 +0100
Subject: [PATCH] Document owner_shadow_root

---
 components/script/dom/node.rs       | 10 +++++++---
 components/script/dom/shadowroot.rs |  7 +++----
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 7c50e4ae69d..22e157f3132 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -125,6 +125,8 @@ pub struct Node {
     owner_doc: MutNullableDom<Document>,
 
     /// The shadow root this node belongs to.
+    /// This is None if the node is not in a shadow tree or
+    /// if it is a ShadowRoot.
     owner_shadow_root: MutNullableDom<ShadowRoot>,
 
     /// The live list of children return by .childNodes.
@@ -284,11 +286,10 @@ impl Node {
 
         for node in new_child.traverse_preorder(ShadowIncluding::No) {
             if parent_in_shadow_tree {
-                if let Some(shadow_root) = self.downcast::<ShadowRoot>() {
-                    node.set_owner_shadow_root(&*shadow_root);
-                } else if let Some(shadow_root) = self.owner_shadow_root() {
+                if let Some(shadow_root) = self.owner_shadow_root() {
                     node.set_owner_shadow_root(&*shadow_root);
                 }
+                debug_assert!(node.owner_shadow_root().is_some());
             }
             node.set_flag(NodeFlags::IS_IN_DOC, parent_in_doc);
             node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, parent_in_shadow_tree);
@@ -930,6 +931,9 @@ impl Node {
     }
 
     pub fn owner_shadow_root(&self) -> Option<DomRoot<ShadowRoot>> {
+        if let Some(ref shadow_root) = self.downcast::<ShadowRoot>() {
+            return Some(DomRoot::from_ref(shadow_root));
+        }
         self.owner_shadow_root.get()
     }
 
diff --git a/components/script/dom/shadowroot.rs b/components/script/dom/shadowroot.rs
index fb38c5531c6..078c937d701 100644
--- a/components/script/dom/shadowroot.rs
+++ b/components/script/dom/shadowroot.rs
@@ -44,10 +44,9 @@ impl ShadowRoot {
     #[allow(unrooted_must_root)]
     fn new_inherited(host: &Element, document: &Document) -> ShadowRoot {
         let document_fragment = DocumentFragment::new_inherited(document);
-        document_fragment
-            .upcast::<Node>()
-            .set_flag(NodeFlags::IS_IN_SHADOW_TREE, true);
-        document_fragment.upcast::<Node>().set_flag(
+        let node = document_fragment.upcast::<Node>();
+        node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, true);
+        node.set_flag(
             NodeFlags::IS_CONNECTED,
             host.upcast::<Node>().is_connected(),
         );