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

<!-- Either: -->
- [X] There are tests for these changes

---------

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

components/url/lib.rs

@@ -224,33 +224,7 @@ impl ServoUrl {
             return true;
         }
         // Step 3
-        self.is_origin_trustworthy()
-    }
-
-    /// <https://w3c.github.io/webappsec-secure-contexts/#is-origin-trustworthy>
-    pub fn is_origin_trustworthy(&self) -> bool {
-        // Step 1
-        if !self.origin().is_tuple() {
-            return false;
-        }
-
-        // Step 3
-        if self.scheme() == "https" || self.scheme() == "wss" {
-            true
-        // Steps 4-5
-        } else if self.host().is_some() {
-            let host = self.host_str().unwrap();
-            // Step 4
-            if let Ok(ip_addr) = host.parse::<IpAddr>() {
-                ip_addr.is_loopback()
-            // Step 5
-            } else {
-                host == "localhost" || host.ends_with(".localhost")
-            }
-        // Step 6
-        } else {
-            self.scheme() == "file"
-        }
+        self.origin().is_potentially_trustworthy()
     }
 }