Check all ancestor navigable trustworthiness for mixed content (#36157)

Propagate through documents a flag that represents if any of the
ancestor navigables has a potentially trustworthy origin.

The "potentially trustworthy origin" concept appears to have gotten
confused in a couple of places and we were instead testing if a URL had
"potentially trustworthy" properties.

The main test for the ancestor navigables is
[mixed-content/nested-iframes](https://github.com/web-platform-tests/wpt/blob/master/mixed-content/nested-iframes.window.js)

---
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- [X] `./mach build -d` does not report any errors
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- [X] These changes fix #36108 

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---------

Signed-off-by: Sebastian C <sebsebmc@gmail.com>

components/script/dom/xmldocument.rs

@@ -43,6 +43,7 @@ impl XMLDocument {
         source: DocumentSource,
         doc_loader: DocumentLoader,
         inherited_insecure_requests_policy: Option<InsecureRequestsPolicy>,
+        has_trustworthy_ancestor_origin: bool,
     ) -> XMLDocument {
         XMLDocument {
             document: Document::new_inherited(
@@ -62,6 +63,7 @@ impl XMLDocument {
                 false,
                 false,
                 inherited_insecure_requests_policy,
+                has_trustworthy_ancestor_origin,
             ),
         }
     }
@@ -79,6 +81,7 @@ impl XMLDocument {
         source: DocumentSource,
         doc_loader: DocumentLoader,
         inherited_insecure_requests_policy: Option<InsecureRequestsPolicy>,
+        has_trustworthy_ancestor_origin: bool,
         can_gc: CanGc,
     ) -> DomRoot<XMLDocument> {
         let doc = reflect_dom_object(
@@ -94,6 +97,7 @@ impl XMLDocument {
                 source,
                 doc_loader,
                 inherited_insecure_requests_policy,
+                has_trustworthy_ancestor_origin,
             )),
             window,
             can_gc,