Bug 1560294 - Relax frameId check in Page.navigate. r=remote-protocol-reviewers,ato

This assertion was mostly meant to warn about this being unimplemented when you were trying to target an iframe.
If frameId refers to the top level tab document, that is fine. This method will work as expected.

Differential Revision: https://phabricator.services.mozilla.com/D35426

--HG--
extra : moz-landing-system : lando

remote/domains/content/Page.jsm

@@ -51,7 +51,7 @@ class Page extends ContentProcessDomain {
   }
 
   async navigate({url, referrer, transitionType, frameId} = {}) {
-    if (frameId) {
+    if (frameId && frameId != this.content.windowUtils.outerWindowID) {
       throw new UnsupportedError("frameId not supported");
     }