[Chromium] Remove unused WebNode::hasEventListeners API
https://bugs.webkit.org/show_bug.cgi?id=112529

Reviewed by James Robinson.

This API no longer has any callers and can be removed.

* public/WebNode.h:
* src/WebNode.cpp:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146031 268f45cc-cd09-0410-ab3c-d52691b4dbfc