Fire an event when a menu list option becomes unselected.

Source/modules/accessibility/AXMenuListPopup.h

Index: Source/modules/accessibility/AXMenuListPopup.h
diff --git a/Source/modules/accessibility/AXMenuListPopup.h b/Source/modules/accessibility/AXMenuListPopup.h
index 1b61b1287515937bd68ece63778e794920942855..dc39bf92a74fa1ab6452507866a062e99df31a9e 100644
--- a/Source/modules/accessibility/AXMenuListPopup.h
+++ b/Source/modules/accessibility/AXMenuListPopup.h
@@ -58,6 +58,8 @@ private:
     virtual bool computeAccessibilityIsIgnored() const override;
 
     AXMenuListOption* menuListOptionAXObject(HTMLElement*) const;
+
+    int m_activeIndex;

[Mike West, 2015/03/19 12:34:21]

This would be better as `unsigned`, as allowing negative indices into arrays is
not a wonderful idea. But, looking at HTMLSelectElement, there doesn't seem to
be anything else you could hook into. That's unfortunate. :/

Would you mind adding a note about `-1`'s magicness?

[dmazzoni, 2015/03/20 04:56:36]

Good idea, done.

 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXMenuListPopup, isMenuListPopup());