Remove PlatformEvent it is no longer used.

third_party/WebKit/Source/core/html/HTMLSelectElement.cpp

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights
  * reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
@@ skipping 1268 matching lines @@
       if (!m_activeSelectionState)
         return;
     }
 
     // The key handling below shouldn't be used for non spatial navigation
     // mode Mac
     if (LayoutTheme::theme().popsMenuByArrowKeys() &&
         !isSpatialNavigationEnabled(document().frame()))
       return;
 
-    int ignoreModifiers = PlatformEvent::ShiftKey | PlatformEvent::CtrlKey |
-                          PlatformEvent::AltKey | PlatformEvent::MetaKey;
+    int ignoreModifiers = WebInputEvent::ShiftKey | WebInputEvent::ControlKey |
+                          WebInputEvent::AltKey | WebInputEvent::MetaKey;
     if (keyEvent->modifiers() & ignoreModifiers)
       return;
 
     const String& key = keyEvent->key();
     bool handled = true;
     const ListItems& listItems = this->listItems();
     HTMLOptionElement* option = selectedOption();
     int listIndex = option ? option->listIndex() : -1;
 
     if (key == "ArrowDown" || key == "ArrowRight")
@@ skipping 740 matching lines @@
   m_popupUpdater = nullptr;
 }
 
 void HTMLSelectElement::didMutateSubtree() {
   DCHECK(popupIsVisible());
   DCHECK(m_popup);
   m_popup->updateFromElement(PopupMenu::ByDOMChange);
 }
 
 }  // namespace blink