Avoid using !OS() constructs.

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 2074 matching lines @@
         HitTestResult result(windowPoint);
         renderView->hitTest(request, result);
         return result.scrollbar();
     }
 
     return false;
 }
 
 bool EventHandler::shouldTurnVerticalTicksIntoHorizontal(const HitTestResult& result, const PlatformWheelEvent& event) const
 {
-#if OS(UNIX) && !OS(MACOSX)
+#if OS(WINDOWS) || OS(MACOSX)

[abarth-chromium, 2013/09/09 17:26:24]

Should Android do this too?

+    UNUSED_PARAM(result);
+    UNUSED_PARAM(event);
+    return false;
+#else
     // GTK+ must scroll horizontally if the mouse pointer is on top of the
     // horizontal scrollbar while scrolling with the wheel.
     // This code comes from gtk/EventHandlerGtk.cpp.
     return !event.hasPreciseScrollingDeltas() && result.scrollbar() && result.scrollbar()->orientation() == HorizontalScrollbar;
-#else
-    UNUSED_PARAM(result);
-    UNUSED_PARAM(event);
-    return false;
 #endif
 }
 
 bool EventHandler::handleWheelEvent(const PlatformWheelEvent& e)
 {
 #define RETURN_WHEEL_EVENT_HANDLED() \
     { \
         setFrameWasScrolledByUser(); \
         return true; \
     }
@@ skipping 1733 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore