[SlimNav] Followup to 'use targetURL when reloading restore session error pages.'

Tighten up some of the logic for when to apply the targetURL fix.  Only target
real relow pages, not renderer initated navigations (such as restoration) and
back forward navigations.

Bug: 1002656
Change-Id: I837257128784167d2a1cdd6e305952aaea3df7bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1797703
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Ali Juma <ajuma@chromium.org>
Auto-Submit: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695701}

ios/web/navigation/wk_based_navigation_manager_impl.mm

@@ -200,8 +200,9 @@ void WKBasedNavigationManagerImpl::AddPendingItem(
   // When reloading an target url redirect page, re-use the target url as the
   // current item url.
   GURL target_url;
-  if (ui::PageTransitionCoreTypeIs(navigation_type,
-                                   ui::PAGE_TRANSITION_RELOAD) &&
+  if (navigation_type & ui::PAGE_TRANSITION_RELOAD &&
+      !(navigation_type & ui::PAGE_TRANSITION_FORWARD_BACK) &&
+      initiation_type == NavigationInitiationType::BROWSER_INITIATED &&
       web::wk_navigation_util::IsRestoreSessionUrl(current_item_url) &&
       web::wk_navigation_util::ExtractTargetURL(current_item_url,
                                                 &target_url)) {