Bug 865430 - Give dispatched mouse events from a11y an unkown input source. r=surkov

accessible/src/base/nsCoreUtils.cpp

@@ -160,6 +160,7 @@ nsCoreUtils::DispatchMouseEvent(uint32_t aEventType, int32_t aX, int32_t aY,
   event.clickCount = 1;
   event.button = nsMouseEvent::eLeftButton;
   event.time = PR_IntervalNow();
+  event.inputSource = nsIDOMMouseEvent::MOZ_SOURCE_UNKNOWN;
 
   nsEventStatus status = nsEventStatus_eIgnore;
   aPresShell->HandleEventWithTarget(&event, aFrame, aContent, &status);