Bug 1626923 - Remove NsiPrincipal-Geturi in ServiceWorkerPrivateImpl.cpp r=ckerschb

Differential Revision: https://phabricator.services.mozilla.com/D69364

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

dom/serviceworkers/ServiceWorkerPrivateImpl.cpp

@@ -98,7 +98,8 @@ nsresult ServiceWorkerPrivateImpl::Initialize() {
   nsCOMPtr<nsIPrincipal> principal = mOuter->mInfo->Principal();
 
   nsCOMPtr<nsIURI> uri;
-  nsresult rv = principal->GetURI(getter_AddRefs(uri));
+  auto* basePrin = BasePrincipal::Cast(principal);
+  nsresult rv = basePrin->GetURI(getter_AddRefs(uri));
 
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;