Auto merge of #25755 - pshaughn:insertqueue, r=nox

Use CE reaction queue when inserting an element from non-fragment parser

<!-- Please describe your changes on the following line: -->
Changed async_html Tokenizer so it can remember whether it's for a fragment and changed servoparser node insertion to respect the CE queue requirements of https://html.spec.whatwg.org/multipage/parsing.html#insert-a-foreign-element; it passes a WPT test.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #25746

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- [X] There are tests for these changes

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components/script/dom/servoparser/async_html.rs

@@ -206,6 +206,7 @@ pub struct Tokenizer {
     #[ignore_malloc_size_of = "Defined in std"]
     nodes: HashMap<ParseNodeId, Dom<Node>>,
     url: ServoUrl,
+    parsing_algorithm: ParsingAlgorithm,
 }
 
 impl Tokenizer {
@@ -219,12 +220,18 @@ impl Tokenizer {
         // Messages from HtmlTokenizer and Sink (parser thread) to Tokenizer (main thread)
         let (to_tokenizer_sender, tokenizer_receiver) = unbounded();
 
+        let algorithm = match fragment_context {
+            Some(_) => ParsingAlgorithm::Fragment,
+            None => ParsingAlgorithm::Normal,
+        };
+
         let mut tokenizer = Tokenizer {
             document: Dom::from_ref(document),
             receiver: tokenizer_receiver,
             html_tokenizer_sender: to_html_tokenizer_sender,
             nodes: HashMap::new(),
             url: url,
+            parsing_algorithm: algorithm,
         };
         tokenizer.insert_node(0, Dom::from_ref(document.upcast()));
 
@@ -352,7 +359,7 @@ impl Tokenizer {
             .GetParentNode()
             .expect("append_before_sibling called on node without parent");
 
-        super::insert(parent, Some(sibling), node);
+        super::insert(parent, Some(sibling), node, self.parsing_algorithm);
     }
 
     fn append(&mut self, parent: ParseNodeId, node: NodeOrText) {
@@ -364,7 +371,7 @@ impl Tokenizer {
         };
 
         let parent = &**self.get_node(&parent);
-        super::insert(parent, None, node);
+        super::insert(parent, None, node, self.parsing_algorithm);
     }
 
     fn has_parent_node(&self, node: ParseNodeId) -> bool {

components/script/dom/servoparser/mod.rs

@@ -950,12 +950,29 @@ pub struct FragmentContext<'a> {
 }
 
 #[allow(unrooted_must_root)]
-fn insert(parent: &Node, reference_child: Option<&Node>, child: NodeOrText<Dom<Node>>) {
+fn insert(
+    parent: &Node,
+    reference_child: Option<&Node>,
+    child: NodeOrText<Dom<Node>>,
+    parsing_algorithm: ParsingAlgorithm,
+) {
     match child {
         NodeOrText::AppendNode(n) => {
+            // https://html.spec.whatwg.org/multipage/#insert-a-foreign-element
+            // applies if this is an element; if not, it may be
+            // https://html.spec.whatwg.org/multipage/#insert-a-comment
+            let element_in_non_fragment =
+                parsing_algorithm != ParsingAlgorithm::Fragment && n.is::<Element>();
+            if element_in_non_fragment {
+                ScriptThread::push_new_element_queue();
+            }
             parent.InsertBefore(&n, reference_child).unwrap();
+            if element_in_non_fragment {
+                ScriptThread::pop_current_element_queue();
+            }
         },
         NodeOrText::AppendText(t) => {
+            // https://html.spec.whatwg.org/multipage/#insert-a-character
             let text = reference_child
                 .and_then(Node::GetPreviousSibling)
                 .or_else(|| parent.GetLastChild())
@@ -1105,7 +1122,7 @@ impl TreeSink for Sink {
             .GetParentNode()
             .expect("append_before_sibling called on node without parent");
 
-        insert(&parent, Some(&*sibling), new_node);
+        insert(&parent, Some(&*sibling), new_node, self.parsing_algorithm);
     }
 
     fn parse_error(&mut self, msg: Cow<'static, str>) {
@@ -1122,7 +1139,7 @@ impl TreeSink for Sink {
     }
 
     fn append(&mut self, parent: &Dom<Node>, child: NodeOrText<Dom<Node>>) {
-        insert(&parent, None, child);
+        insert(&parent, None, child, self.parsing_algorithm);
     }
 
     fn append_based_on_parent_node(