--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -7371,36 +7371,29 @@ nsresult nsHttpChannel::ComputeCrossOrig
       mResponseHead ? mResponseHead : mCachedResponseHead;
   if (!head) {
     return NS_ERROR_NOT_AVAILABLE;
   }
 
   RefPtr<mozilla::dom::BrowsingContext> ctx;
   mLoadInfo->GetBrowsingContext(getter_AddRefs(ctx));
 
-  RefPtr<BrowsingContext> inherit = ctx->GetParent();
-  if (!inherit) {
-    inherit = ctx->GetOpener();
-  }
-
-  if (!inherit || !inherit->Top()->Canonical()->GetCurrentWindowGlobal()) {
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
   // Get the policy of the active document, and the policy for the result.
   nsILoadInfo::CrossOriginOpenerPolicy documentPolicy = ctx->GetOpenerPolicy();
   nsILoadInfo::CrossOriginOpenerPolicy resultPolicy =
       nsILoadInfo::OPENER_POLICY_NULL;
   Unused << GetCrossOriginOpenerPolicy(documentPolicy, &resultPolicy);
 
+  if (!ctx->Canonical()->GetCurrentWindowGlobal()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
   // We use the top window principal as the documentOrigin
-  nsCOMPtr<nsIPrincipal> documentOrigin = inherit->Top()
-                                              ->Canonical()
-                                              ->GetCurrentWindowGlobal()
-                                              ->DocumentPrincipal();
+  nsCOMPtr<nsIPrincipal> documentOrigin =
+      ctx->Canonical()->GetCurrentWindowGlobal()->DocumentPrincipal();
   nsCOMPtr<nsIPrincipal> resultOrigin;
 
   nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(
       this, getter_AddRefs(resultOrigin));
 
   bool compareResult = CompareCrossOriginOpenerPolicies(
       documentPolicy, documentOrigin, resultPolicy, resultOrigin);