Bug 1933331 - [bidi] Update initiatorType and destination for top level document loads r=webdriver-reviewers,Sasha

The platform API currently returns values for initiatorType and destination
for top level document loads, but according to the HTML spec they should be null / empty.

The implementation in WebDriver BiDi NetworkRequest wrapper is updated to handle this
edge case.

Differential Revision: https://phabricator.services.mozilla.com/D230174

remote/shared/NetworkRequest.sys.mjs

@@ -102,6 +102,10 @@ export class NetworkRequest {
   }
 
   get destination() {
+    if (this.#isTopLevelDocumentLoad()) {
+      return "";
+    }
+
     return this.#channel.loadInfo?.fetchDestination;
   }
 
@@ -127,6 +131,10 @@ export class NetworkRequest {
       return null;
     }
 
+    if (this.#isTopLevelDocumentLoad()) {
+      return null;
+    }
+
     return initiatorType;
   }
 
@@ -501,4 +509,15 @@ export class NetworkRequest {
 
     return navigation ? navigation.navigationId : null;
   }
+
+  #isTopLevelDocumentLoad() {
+    if (!this.#channel.isDocument) {
+      return false;
+    }
+
+    const browsingContext = lazy.TabManager.getBrowsingContextById(
+      this.#contextId
+    );
+    return !browsingContext.parent;
+  }
 }