2c8c727068
This does essentially the same thing, but uses event retargetting to
simulate event.target under shadow DOM. This acts the same as
currentTarget because the node is always in the same scope as the node
where the listener was added. This is polyfilled to work in older
browsers than e.currentTarget and is less likely to have issues with
shadow DOM.
https://www.polymer-project.org/1.0/docs/devguide/events#retargeting
Change-Id: I6fe5afdfddfdc3e21fbca10aef260cac704bea3d
(cherry picked from commit 5b62347cf4)