Remove platform dependency upon page/Settings class which is a layering violation.

Source/core/platform/mac/NSScrollerImpDetails.mm

 /*
  * Copyright (C) 2011 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
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  *
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 #include "config.h"
 #include "RuntimeEnabledFeatures.h"
-#include "core/page/Settings.h"
 #include "core/platform/mac/NSScrollerImpDetails.h"
 
 namespace WebCore {
 
 bool isScrollbarOverlayAPIAvailable()
 {
     static bool apiAvailable;
     static bool shouldInitialize = true;
     if (shouldInitialize) {
         shouldInitialize = false;
         Class scrollerImpClass = NSClassFromString(@"NSScrollerImp");
         Class scrollerImpPairClass = NSClassFromString(@"NSScrollerImpPair");
         apiAvailable = [scrollerImpClass respondsToSelector:@selector(scrollerImpWithStyle:controlSize:horizontal:replacingScrollerImp:)]
                        && [scrollerImpPairClass instancesRespondToSelector:@selector(scrollerStyle)];
     }
     return apiAvailable;
 }
 
 NSScrollerStyle recommendedScrollerStyle() {
     if (RuntimeEnabledFeatures::overlayScrollbarsEnabled())
         return NSScrollerStyleOverlay;
     if ([NSScroller respondsToSelector:@selector(preferredScrollerStyle)])
         return [NSScroller preferredScrollerStyle];
     return NSScrollerStyleLegacy;
 }
 
 }