Remove special wheel handling path from ScrollableArea

Source/core/frame/RootFrameViewport.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef RootFrameViewport_h
 #define RootFrameViewport_h
 
 #include "core/CoreExport.h"
 #include "platform/scroll/ScrollableArea.h"
 
@@ skipping 50 matching lines @@
     GraphicsLayer* layerForContainer() const override;
     GraphicsLayer* layerForScrolling() const override;
     GraphicsLayer* layerForHorizontalScrollbar() const override;
     GraphicsLayer* layerForVerticalScrollbar() const override;
     ScrollResultOneDimensional userScroll(ScrollDirectionPhysical, ScrollGranularity, float delta = 1) override;
     bool scrollAnimatorEnabled() const override;
     HostWindow* hostWindow() const override;
     void serviceScrollAnimations(double) override;
     void updateCompositorScrollAnimations() override;
     ScrollBehavior scrollBehaviorStyle() const override;
-    // TODO(bokan): This method should be removed. It should be replaced by
-    // making EventHandler::handleWheelEvent unpack the WheelEvent and make a
-    // call to this class' scroll method.
-    ScrollResult handleWheel(const PlatformWheelEvent&) override;
 
 private:
     RootFrameViewport(ScrollableArea& visualViewport, ScrollableArea& layoutViewport, bool invertScrollOrder);
 
     DoublePoint scrollOffsetFromScrollAnimators() const;
 
     // If either of the layout or visual viewports are scrolled explicitly (i.e. not
     // through this class), their updated offset will not be reflected in this class'
     // animator so use this method to pull updated values when necessary.
     void updateScrollAnimator();
 
     ScrollableArea& visualViewport() const { ASSERT(m_visualViewport); return *m_visualViewport; }
     ScrollableArea& layoutViewport() const { ASSERT(m_layoutViewport); return *m_layoutViewport; }
 
     RawPtrWillBeMember<ScrollableArea> m_visualViewport;
     RawPtrWillBeMember<ScrollableArea> m_layoutViewport;
 
     // Experimental flag. If the experiment is enabled, scroll the visual viewport first,
     // the bubble scrolls to the layout viewport.
     bool m_invertScrollOrder;
 };
 
 } // namespace blink
 
 #endif // RootFrameViewport_h