[ios] Do not show SSL interstitial if cert is absent or cannot be parsed

ios/web/web_state/error_translation_util.mm

 // Copyright 2015 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/error_translation_util.h"
 
 #include <CFNetwork/CFNetwork.h>
 
 #import "base/ios/ns_error_util.h"
 #include "base/mac/scoped_nsobject.h"
@@ skipping 139 matching lines @@
       base::ios::GetFinalUnderlyingErrorFromError(error);
 
   NSInteger net_error_code = net::ERR_FAILED;
   if ([underlying_error.domain isEqualToString:NSURLErrorDomain] ||
       [underlying_error.domain
           isEqualToString:static_cast<NSString*>(kCFErrorDomainCFNetwork)]) {
     // Attempt to translate NSURL and CFNetwork error codes into their
     // corresponding net error codes.
     GetNetErrorFromIOSErrorCode(underlying_error.code, &net_error_code);
   }
+  return NetErrorFromError(error, net_error_code);
+}
 
+NSError* NetErrorFromError(NSError* error, NSInteger net_error_code) {
+  DCHECK(error);
   NSString* net_error_domain =
       [NSString stringWithUTF8String:net::kErrorDomain];
   NSError* net_error = [NSError errorWithDomain:net_error_domain
                                            code:net_error_code
                                        userInfo:nil];
   return base::ios::ErrorWithAppendedUnderlyingError(error, net_error);
 }
 
 }  // namespace web