events,lib: don't require EE#listenerCount()

Fixes: nodejs#2655
Ref: 8f58fb9
PR-URL: nodejs#2661
Reviewed-By: thefourtheye - Sakthipriyan Vairamani <[email protected]>
Reviewed-By: cjihrig - Colin Ihrig <[email protected]>
Reviewed-By: jasnell - James M Snell <[email protected]>

2015-09-02 io.js v3.3.0 Release

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