Populates sourceDevice attribute into MouseEvent

LayoutTests/fast/events/uievent-with-inputdevice.html

Index: LayoutTests/fast/events/uievent-with-inputdevice.html
diff --git a/LayoutTests/fast/events/uievent-with-inputdevice.html b/LayoutTests/fast/events/uievent-with-inputdevice.html
index d5ef4d67d12af2d22e49541a49af41a1b2e8085f..4bb33861f9e0cc72e0e59f571f30ff5851e8e051 100644
--- a/LayoutTests/fast/events/uievent-with-inputdevice.html
+++ b/LayoutTests/fast/events/uievent-with-inputdevice.html
@@ -17,5 +17,13 @@
     var touchevent = document.createEvent("TouchEvent");
     shouldBeNonNull("touchevent");
     shouldBeNull("touchevent.sourceDevice");
+    
+    document.addEventListener("click", function(event) {

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

The other tests look at mousedown/mousemove/mouseup.
It would probably make sense to test those here as well.

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

Done.

+      shouldBeNonNull("event");
+      shouldBeNull("event.sourceDevice");
+    });
+
+    var e = new MouseEvent('click');
+    document.dispatchEvent(e);
 
-</script>
+</script>