devtools: Allow highlighting elements from the inspector (#35822)

This change connects the `HighlighterActor` from the devtools with the
document, which will draw a blue rectangle over any highlighted dom
node.



https://github.com/user-attachments/assets/571b2dab-497f-4102-9e55-517cdcc040ba




---
<!-- 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 do not require tests because we don't have devtools
tests

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

components/script/dom/window.rs

@@ -2142,6 +2142,8 @@ impl Window {
             .or_else(|| document.GetDocumentElement())
             .map(|root| root.upcast::<Node>().to_trusted_node_address());
 
+        let highlighted_dom_node = document.highlighted_dom_node().map(|node| node.to_opaque());
+
         // Send new document and relevant styles to layout.
         let reflow = ReflowRequest {
             reflow_info: Reflow {
@@ -2161,6 +2163,7 @@ impl Window {
                 .image_animation_manager_mut()
                 .take_image_animate_set(),
             theme: self.theme.get(),
+            highlighted_dom_node,
         };
 
         let Some(results) = self.layout.borrow_mut().reflow(reflow) else {