Provide a std::vector compliant empty() method for WebVector.

third_party/WebKit/Source/web/ExternalPopupMenu.cpp

 /*
  * Copyright (C) 2010 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 66 matching lines @@
 bool ExternalPopupMenu::showInternal() {
   // Blink core reuses the PopupMenu of an element.  For simplicity, we do
   // recreate the actual external popup everytime.
   if (m_webExternalPopupMenu) {
     m_webExternalPopupMenu->close();
     m_webExternalPopupMenu = 0;
   }
 
   WebPopupMenuInfo info;
   getPopupMenuInfo(info, *m_ownerElement);
-  if (info.items.isEmpty())
+  if (info.items.empty())
     return false;
   WebLocalFrameImpl* webframe =
       WebLocalFrameImpl::fromFrame(m_localFrame.get());
   m_webExternalPopupMenu =
       webframe->client()->createExternalPopupMenu(info, this);
   if (m_webExternalPopupMenu) {
     LayoutObject* layoutObject = m_ownerElement->layoutObject();
     if (!layoutObject || !layoutObject->isBox())
       return false;
     FloatQuad quad(toLayoutBox(layoutObject)
@@ skipping 205 matching lines @@
     if (ownerElement.itemIsDisplayNone(*items[i]))
       continue;
     if (popupMenuItemIndex == i)
       return indexTracker;
     ++indexTracker;
   }
   return -1;
 }
 
 }  // namespace blink