Remove some dead scrolling paths and unused params

Source/platform/HostWindow.h

 /*
  * Copyright (C) 2008 Apple 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 31 matching lines @@
 
 class PLATFORM_EXPORT HostWindow {
     WTF_MAKE_NONCOPYABLE(HostWindow); WTF_MAKE_FAST_ALLOCATED;
 public:
     HostWindow() { }
     virtual ~HostWindow() { }
 
     // Requests the host invalidate the contents and the root view.
     virtual void invalidateContentsAndRootView(const IntRect& updateRect) = 0;
 
-    // Requests the host scroll backingstore by the specified delta, rect to scroll, and clip rect.
-    virtual void scroll(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect) = 0;
+    virtual void scroll(const IntRect& clipRect) = 0;
 
     // Requests the host invalidate the contents, not the root view. This is the slow path for scrolling.
     virtual void invalidateContentsForSlowScroll(const IntRect& updateRect) = 0;
 
     // Methods for doing coordinate conversions to screen coordinates.
     virtual IntRect rootViewToScreen(const IntRect&) const = 0;
 
     virtual blink::WebScreenInfo screenInfo() const = 0;
 
     virtual void scheduleAnimation() = 0;
 };
 
 } // namespace WebCore
 
 #endif // HostWindow_h