Don't allow deferred frames to create new windows.

third_party/WebKit/Source/web/ChromeClientImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 340 matching lines @@
 }
 
 } // namespace
 
 Page* ChromeClientImpl::createWindow(LocalFrame* frame, const FrameLoadRequest& r, const WindowFeatures& features,
     NavigationPolicy navigationPolicy)
 {
     if (!m_webView->client())
         return nullptr;
 
+    if (!frame->page() || frame->page()->defersLoading())
+        return nullptr;
+
     WebNavigationPolicy policy = effectiveNavigationPolicy(navigationPolicy, features);
     DCHECK(frame->document());
     Fullscreen::fullyExitFullscreen(*frame->document());
 
     WebViewImpl* newView = toWebViewImpl(
         m_webView->client()->createView(WebLocalFrameImpl::fromFrame(frame), WrappedResourceRequest(r.resourceRequest()), features, r.frameName(), policy, r.getShouldSetOpener() == NeverSetOpener || features.noopener));
     if (!newView)
         return nullptr;
     return newView->page();
 }
@@ skipping 748 matching lines @@
 {
     return wrapUnique(m_webView->scheduler()->createFrameScheduler(blameContext).release());
 }
 
 double ChromeClientImpl::lastFrameTimeMonotonic() const
 {
     return m_webView->lastFrameTimeMonotonic();
 }
 
 } // namespace blink