Populates sourceDevice attribute into MouseEvent

Source/core/input/InputDevice.h

Index: Source/core/input/InputDevice.h
diff --git a/Source/core/input/InputDevice.h b/Source/core/input/InputDevice.h
index 80238f0e90978aac33bef5b6c73a371356c0f3d0..514e64b3caccfae824cfaaee317a31598c7a031a 100644
--- a/Source/core/input/InputDevice.h
+++ b/Source/core/input/InputDevice.h
@@ -20,6 +20,9 @@ public:
     // This return a static local InputDevice pointer which has firesTouchEvents set to be true.
     static InputDevice* touchEventInstance();
 
+    // This return a static local InputDevice pointer which has firesTouchEvents set to be false.
+    static InputDevice* nonTouchEventInstance();

[tdresser, 2015/06/12 13:06:54]

I should have commented on this sooner - I think we can find better names for
these.

Having mouseEvent->sourceDevice() == InputDevice::touchEventInstance() doesn't
make much sense.

Perhaps call these firesTouchEventsInstance and doesntFireTouchEventsInstance?

I'm not completely happy with that naming either, but I do like it better.

[lanwei, 2015/06/16 21:51:43]

Done.

+
     static InputDevice* create(bool firesTouchEvents)
     {
         return new InputDevice(firesTouchEvents);