Fix shadowhost to adjusted current node

Signed-off-by: batu_hoang <longvatrong111@gmail.com>

Author: longvatrong111

html5ever/src/tree_builder/mod.rs

@@ -1377,6 +1377,7 @@ where
         self.insert_element(Push, ns!(html), name, vec![])
     }
 
+    // https://html.spec.whatwg.org/multipage/parsing.html#insert-an-element-at-the-adjusted-insertion-location
     fn insert_foreign_element(
         &self,
         tag: Tag,
@@ -1397,6 +1398,8 @@ where
     }
     //§ END
 
+    // https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inhead
+    // A start tag whose tag name is "template"
     fn should_attach_declarative_shadow(&self, tag: &Tag) -> bool {
         let adjusted_insertion_location = self.appropriate_place_for_insertion(None);
 
@@ -1411,7 +1414,7 @@ where
         // template start tag's shadowrootmode is not in the none state
         let is_shadow_root_mode = tag.attrs.iter().any(|attr| {
             attr.name.local == local_name!("shadowrootmode")
-                && (attr.value.to_string() == *"open" || attr.value.to_string() == *"close")
+                && (attr.value.to_string() == *"open" || attr.value.to_string() == *"closed")
         });
 
         // Check if intended_parent's document allows declarative shadow roots
@@ -1435,6 +1438,8 @@ where
         is_shadow_root_mode && allow_declarative_shadow_roots && adjusted_current_node_not_topmost
     }
 
+    // https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inhead
+    // A start tag whose tag name is "template"
     fn attach_declarative_shadow(
         &self,
         tag: &Tag,

html5ever/src/tree_builder/rules.rs

@@ -160,7 +160,11 @@ where
                     self.template_modes.borrow_mut().push(InTemplate);
 
                     if (self.should_attach_declarative_shadow(&tag)) {
-                        let shadow_host = self.open_elems.borrow().last().unwrap().clone();
+                        let mut shadow_host = self.open_elems.borrow().last().unwrap().clone();
+                        if self.is_fragment() && self.open_elems.borrow().len() == 1 {
+                            shadow_host = self.context_elem.borrow().clone().unwrap();
+                        }
+
                         let template = self.insert_foreign_element(tag.clone(), ns!(html), true);
 
                         if self.attach_declarative_shadow(&tag, &shadow_host, &template).is_err() {