Properly handle a NULL webwidget returned from WebViewClient::createPopupMenu

Source/web/PopupContainer.cpp

 /*
  * Copyright (c) 2011, Google Inc. All rights reserved.
  *
  * 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 454 matching lines @@
     return listBox()->m_popupClient->itemToolTip(listBox()->m_selectedIndex);
 }
 
 void PopupContainer::popupOpened(const IntRect& bounds)
 {
     WebViewImpl* webView = WebViewImpl::fromPage(m_frameView->frame().page());
     if (!webView->client())
         return;
 
     WebWidget* webwidget = webView->client()->createPopupMenu(WebPopupTypeSelect);
+    if (!webwidget)
+        return;
     // We only notify when the WebView has to handle the popup, as when
     // the popup is handled externally, the fact that a popup is showing is
     // transparent to the WebView.
     webView->popupOpened(this);
     toWebPopupMenuImpl(webwidget)->initialize(this, bounds);
 }
 
 void PopupContainer::getPopupMenuInfo(WebPopupMenuInfo* info)
 {
     const Vector<PopupItem*>& inputItems = popupData();
@@ skipping 26 matching lines @@
     }
 
     info->itemHeight = menuItemHeight();
     info->itemFontSize = menuItemFontSize();
     info->selectedIndex = selectedIndex();
     info->items.swap(outputItems);
     info->rightAligned = menuStyle().textDirection() == RTL;
 }
 
 } // namespace blink