Populates sourceDevice attribute into MouseEvent

Source/core/events/UIEvent.h

Index: Source/core/events/UIEvent.h
diff --git a/Source/core/events/UIEvent.h b/Source/core/events/UIEvent.h
index c01f7c6b26d090c72f2dbe7d5b434e5bca9b8467..bc46e1e205590e16b8186d995c71441842d0aa95 100644
--- a/Source/core/events/UIEvent.h
+++ b/Source/core/events/UIEvent.h
@@ -55,9 +55,12 @@ public:
 
     void initUIEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView>, int detail);
 
+    void initUIEvent(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView>, int detail, InputDevice* sourceDevice);
+
     AbstractView* view() const { return m_view.get(); }
     int detail() const { return m_detail; }
     InputDevice* sourceDevice() const { return m_sourceDevice.get(); }
+    void setSourceDevice(InputDevice* sourceDevice) { m_sourceDevice = sourceDevice; }
 
     virtual const AtomicString& interfaceName() const override;
     virtual bool isUIEvent() const override final;