servo: Merge #19218 - added navigation start for interactive metrics (from avadacatavra:nav-start); r=jdm

<!-- Please describe your changes on the following line: -->
 follow up from  #18670, fixing #19099

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #19099 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Source-Repo: https://github.com/servo/servo
Source-Revision: 7d13e5b83c346d06dc68f22857a17f30ea797402

servo/components/script/script_thread.rs

@@ -1248,6 +1248,9 @@ impl ScriptThread {
         for (doc_id, doc) in self.documents.borrow().iter() {
            if let Some(pipeline_id) = pipeline_id {
                 if pipeline_id == doc_id && end - start > MAX_TASK_NS {
+                    if opts::get().print_pwm {
+                        println!("Task took longer than max allowed ({:?}) {:?}", category, end - start);
+                    }
                     doc.start_tti();
                 }
             }
@@ -2229,6 +2232,7 @@ impl ScriptThread {
         let parse_input = DOMString::new();
 
         document.set_https_state(metadata.https_state);
+        document.set_navigation_start(incomplete.navigation_start_precise);
 
         if is_html_document == IsHTMLDocument::NonHTMLDocument {
             ServoParser::parse_xml_document(&document, parse_input, final_url);