Add rails to input wheel events.

Source/web/WebInputEventConversion.cpp

Index: Source/web/WebInputEventConversion.cpp
diff --git a/Source/web/WebInputEventConversion.cpp b/Source/web/WebInputEventConversion.cpp
index 20b0fc759bae4afa6d5ce6acfeb7dd1ec0086273..d1a6665a6dea79da511c3cb05e6218f90bd0ef44 100644
--- a/Source/web/WebInputEventConversion.cpp
+++ b/Source/web/WebInputEventConversion.cpp
@@ -200,6 +200,7 @@ PlatformWheelEventBuilder::PlatformWheelEventBuilder(Widget* widget, const WebMo
 
     m_hasPreciseScrollingDeltas = e.hasPreciseScrollingDeltas;
     m_canScroll = e.canScroll;
+    m_railsMode = static_cast<PlatformEvent::RailsMode>(e.railsMode);
 #if OS(MACOSX)
     m_phase = static_cast<PlatformWheelEventPhase>(e.phase);
     m_momentumPhase = static_cast<PlatformWheelEventPhase>(e.momentumPhase);
@@ -649,6 +650,7 @@ WebMouseWheelEventBuilder::WebMouseWheelEventBuilder(const Widget* widget, const
     wheelTicksY = event.ticksY();
     scrollByPage = event.deltaMode() == WheelEvent::DOM_DELTA_PAGE;
     canScroll = event.canScroll();
+    railsMode = static_cast<RailsMode>(event.railsMode());
 }
 
 WebKeyboardEventBuilder::WebKeyboardEventBuilder(const KeyboardEvent& event)