Remove invalid DCHECK in [CRWSessionController addPendingItem].

ios/web/navigation/crw_session_controller.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/navigation/crw_session_controller.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 269 matching lines @@
   DCHECK(!_navigationManager ||
          _navigationManager->GetBrowserState() == _browserState);
 }
 
 - (void)addPendingItem:(const GURL&)url
                    referrer:(const web::Referrer&)ref
                  transition:(ui::PageTransition)trans
              initiationType:(web::NavigationInitiationType)initiationType
     userAgentOverrideOption:(web::NavigationManager::UserAgentOverrideOption)
                                 userAgentOverrideOption {
-  // Server side redirects are handled by updating existing pending item instead
-  // of adding a new item.
-  DCHECK((trans & ui::PAGE_TRANSITION_SERVER_REDIRECT) == 0);
-
   [self discardTransientItem];
   self.pendingItemIndex = -1;
 
   if (![self shouldCreatePendingItemWithURL:url
                                  transition:trans
                     userAgentOverrideOption:userAgentOverrideOption]) {
     return;
   }
 
   _pendingItem = [self itemWithURL:url
@@ skipping 352 matching lines @@
   return item;
 }
 
 - (BOOL)isRedirectTransitionForItemAtIndex:(size_t)index {
   DCHECK_LT(index, self.items.size());
   ui::PageTransition transition = self.items[index]->GetTransitionType();
   return (transition & ui::PAGE_TRANSITION_IS_REDIRECT_MASK) ? YES : NO;
 }
 
 @end