[ios] Made goToItemAtIndex: safe for release builds.

ios/web/web_state/ui/crw_web_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/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 2258 matching lines @@
       [_delegate webLoadCancelled:_URLOnStartLoading];
       break;
     case web::PAGE_LOADED:
       break;
   }
 }
 
 - (void)goToItemAtIndex:(int)index {
   CRWSessionController* sessionController = self.sessionController;
   NSArray* entries = sessionController.entries;
-  DCHECK_LT(static_cast<NSUInteger>(index), entries.count);
-  DCHECK_GE(index, 0);
+  if (index < 0 || index >= static_cast<int>(entries.count)) {
+    NOTREACHED();
+    return;
+  }
 
   if (!_webStateImpl->IsShowingWebInterstitial())
     [self recordStateInHistory];
   CRWSessionEntry* fromEntry = self.sessionController.currentEntry;
 
   NSUserDefaults* userDefaults = [NSUserDefaults standardUserDefaults];
   if (![userDefaults boolForKey:@"PendingIndexNavigationDisabled"]) {
     BOOL sameDocumentNavigation =
         [sessionController isSameDocumentNavigationBetweenEntry:fromEntry
                                                        andEntry:entries[index]];
@@ skipping 3477 matching lines @@
   }
 
   return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
 }
 
 - (NSString*)refererFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:@"Referer"];
 }
 
 @end