--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -2084,17 +2084,20 @@ nsFrameLoader::MaybeCreateDocShell()
   // For example, firstPartyDomain is computed from top-level document, it
   // doesn't exist in the top-level docshell.
   if (parentType == nsIDocShellTreeItem::typeContent &&
       !nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()) &&
       !OwnerIsMozBrowserOrAppFrame()) {
     PrincipalOriginAttributes poa = BasePrincipal::Cast(doc->NodePrincipal())->OriginAttributesRef();
 
     // Assert on the firstPartyDomain from top-level docshell should be empty
-    MOZ_ASSERT_IF(mIsTopLevelContent, attrs.mFirstPartyDomain.IsEmpty());
+    if (mIsTopLevelContent) {
+      MOZ_ASSERT(attrs.mFirstPartyDomain.IsEmpty(),
+                 "top-level docshell shouldn't have firstPartyDomain attribute.");
+    }
 
     // So far we want to make sure InheritFromDocToChildDocShell doesn't override
     // any other origin attribute than firstPartyDomain.
     MOZ_ASSERT(attrs.mAppId == poa.mAppId,
               "docshell and document should have the same appId attribute.");
     MOZ_ASSERT(attrs.mUserContextId == poa.mUserContextId,
               "docshell and document should have the same userContextId attribute.");
     MOZ_ASSERT(attrs.mInIsolatedMozBrowser == poa.mInIsolatedMozBrowser,

--- a/netwerk/protocol/http/HttpBaseChannel.cpp
+++ b/netwerk/protocol/http/HttpBaseChannel.cpp
@@ -2940,40 +2940,41 @@ HttpBaseChannel::SetupReplacementChannel
   if (mLoadInfo) {
     nsCOMPtr<nsILoadInfo> newLoadInfo =
       static_cast<mozilla::LoadInfo*>(mLoadInfo.get())->Clone();
 
     // re-compute the origin attributes of the loadInfo if it's top-level load.
     bool isTopLevelDoc =
       newLoadInfo->GetExternalContentPolicyType() == nsIContentPolicy::TYPE_DOCUMENT;
 
-    nsCOMPtr<nsILoadContext> loadContext;
-    NS_QueryNotificationCallbacks(this, loadContext);
-    DocShellOriginAttributes docShellAttrs;
-    if (loadContext) {
-      loadContext->GetOriginAttributes(docShellAttrs);
+    if (isTopLevelDoc) {
+      nsCOMPtr<nsILoadContext> loadContext;
+      NS_QueryNotificationCallbacks(this, loadContext);
+      DocShellOriginAttributes docShellAttrs;
+      if (loadContext) {
+        loadContext->GetOriginAttributes(docShellAttrs);
+      }
+      MOZ_ASSERT(docShellAttrs.mFirstPartyDomain.IsEmpty(),
+                 "top-level docshell shouldn't have firstPartyDomain attribute.");
+
+      NeckoOriginAttributes attrs = newLoadInfo->GetOriginAttributes();
+
+      MOZ_ASSERT(docShellAttrs.mAppId == attrs.mAppId,
+                "docshell and necko should have the same appId attribute.");
+      MOZ_ASSERT(docShellAttrs.mUserContextId == attrs.mUserContextId,
+                "docshell and necko should have the same userContextId attribute.");
+      MOZ_ASSERT(docShellAttrs.mInIsolatedMozBrowser == attrs.mInIsolatedMozBrowser,
+                "docshell and necko should have the same inIsolatedMozBrowser attribute.");
+      MOZ_ASSERT(docShellAttrs.mPrivateBrowsingId == attrs.mPrivateBrowsingId,
+                 "docshell and necko should have the same privateBrowsingId attribute.");
+
+      attrs.InheritFromDocShellToNecko(docShellAttrs, true, newURI);
+      newLoadInfo->SetOriginAttributes(attrs);
     }
 
-    // top-level docshell shouldn't have firstPartyDomain attribute.
-    MOZ_ASSERT_IF(isTopLevelDoc, docShellAttrs.mFirstPartyDomain.IsEmpty());
-
-    NeckoOriginAttributes attrs = newLoadInfo->GetOriginAttributes();
-
-    MOZ_ASSERT(docShellAttrs.mAppId == attrs.mAppId,
-               "docshell and necko should have the same appId attribute.");
-    MOZ_ASSERT(docShellAttrs.mUserContextId == attrs.mUserContextId,
-               "docshell and necko should have the same userContextId attribute.");
-    MOZ_ASSERT(docShellAttrs.mInIsolatedMozBrowser == attrs.mInIsolatedMozBrowser,
-               "docshell and necko should have the same inIsolatedMozBrowser attribute.");
-    MOZ_ASSERT(docShellAttrs.mPrivateBrowsingId == attrs.mPrivateBrowsingId,
-               "docshell and necko should have the same privateBrowsingId attribute.");
-
-    attrs.InheritFromDocShellToNecko(docShellAttrs, isTopLevelDoc, newURI);
-    newLoadInfo->SetOriginAttributes(attrs);
-
     bool isInternalRedirect =
       (redirectFlags & (nsIChannelEventSink::REDIRECT_INTERNAL |
                         nsIChannelEventSink::REDIRECT_STS_UPGRADE));
     newLoadInfo->AppendRedirectedPrincipal(GetURIPrincipal(), isInternalRedirect);
     newChannel->SetLoadInfo(newLoadInfo);
   }
   else {
     // the newChannel was created with a dummy loadInfo, we should clear