WheelEvent created using document.createEvent() is not properly initialized

Source/core/dom/WheelEvent.cpp

Index: Source/core/dom/WheelEvent.cpp
diff --git a/Source/core/dom/WheelEvent.cpp b/Source/core/dom/WheelEvent.cpp
index 1c000eecec2146a66df376ccae29af9f69281012..bd5c36ef1c78ee54828cd577bb06a16da9a911f4 100644
--- a/Source/core/dom/WheelEvent.cpp
+++ b/Source/core/dom/WheelEvent.cpp
@@ -41,7 +41,10 @@ WheelEventInit::WheelEventInit()
 }
 
 WheelEvent::WheelEvent()
-    : m_deltaMode(DOM_DELTA_PIXEL)
+    : m_deltaX(0)
+    , m_deltaY(0)
+    , m_deltaZ(0)
+    , m_deltaMode(DOM_DELTA_PIXEL)
     , m_directionInvertedFromDevice(false)
 {
     ScriptWrappable::init(this);