Allow HAVE_ACCESSIBILITY to be turned off at build time

webkit/port/platform/mac/ScrollViewMac.mm

 /*
  * Copyright (C) 2004, 2006 Apple Computer, 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 192 matching lines @@
 bool ScrollView::scroll(ScrollDirection direction, ScrollGranularity granularity) {
   NSLog(@"ScrollViewMacSkia::scroll should do something here");
   return true;
 }
 
 NSView* ScrollView::documentView() const {
   // TODO(pinkerton): we really gotta figure out how we're doing scrolling
   return nil;
 }
 
+bool ScrollView::isScrollable() {
+  // placeholder until we pull new ScrollView implementation from WebKit
+  return false;
 }
+
+}