Do not suppress HTTP Authenticaiton in WebController.

ios/chrome/browser/ui/browser_view_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/chrome/browser/ui/browser_view_controller.h"
 
 #import <AssetsLibrary/AssetsLibrary.h>
 #import <MobileCoreServices/MobileCoreServices.h>
 #import <PassKit/PassKit.h>
 #import <Photos/Photos.h>
@@ skipping 2620 matching lines @@
 - (web::JavaScriptDialogPresenter*)javaScriptDialogPresenterForWebState:
     (web::WebState*)webState {
   return _javaScriptDialogPresenter.get();
 }
 
 - (void)webState:(web::WebState*)webState
     didRequestHTTPAuthForProtectionSpace:(NSURLProtectionSpace*)protectionSpace
                       proposedCredential:(NSURLCredential*)proposedCredential
                        completionHandler:(void (^)(NSString* username,
                                                    NSString* password))handler {
+  Tab* tab = LegacyTabHelper::GetTabForWebState(webState);
+  if ([tab isPrerenderTab]) {
+    [tab discardPrerender];
+    if (handler) {
+      handler(nil, nil);
+    }
+    return;
+  }
+
   [self.dialogPresenter runAuthDialogForProtectionSpace:protectionSpace
                                      proposedCredential:proposedCredential
                                                webState:webState
                                       completionHandler:handler];
 }
 
 #pragma mark - FullScreenControllerDelegate methods
 
 - (CGFloat)headerOffset {
   if (IsIPadIdiom())
@@ skipping 2466 matching lines @@
 
 - (UIView*)voiceSearchButton {
   return _voiceSearchButton;
 }
 
 - (id<LogoAnimationControllerOwner>)logoAnimationControllerOwner {
   return [self currentLogoAnimationControllerOwner];
 }
 
 @end