Fixed typo in InterstitialDismissed method name.

ios/web/web_state/web_state_impl.mm

 // Copyright 2013 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/web_state_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 445 matching lines @@
   if (interstitial_) {
     // Store the currently displayed interstitial in a local variable and reset
     // |interstitial_| early.  This is to prevent an infinite loop, as
     // |DontProceed()| internally calls |ClearTransientContentView()|.
     web::WebInterstitial* interstitial = interstitial_;
     interstitial_ = nullptr;
     interstitial->DontProceed();
     // Don't access |interstitial| after calling |DontProceed()|, as it triggers
     // deletion.
     for (auto& observer : observers_)
-      observer.InsterstitialDismissed();
+      observer.InterstitialDismissed();
   }
   [web_controller_ clearTransientContentView];
 }
 
 void WebStateImpl::SendChangeLoadProgress(double progress) {
   for (auto& observer : observers_)
     observer.LoadProgressChanged(progress);
 }
 
 bool WebStateImpl::HandleContextMenu(const web::ContextMenuParams& params) {
@@ skipping 288 matching lines @@
     const LoadCommittedDetails& load_details) {
   for (auto& observer : observers_)
     observer.NavigationItemCommitted(load_details);
 }
 
 WebState* WebStateImpl::GetWebState() {
   return this;
 }
 
 }  // namespace web