Check for removeEventListener before calling it.
Check for removeEventListener before calling it.

Sometimes the iframe exists, but the player doesn't have `removeEventListener`
on it yet.

retrying solving #30

troybetz/react-youtube,compedit/react-youtube,ymortazavi/react-youtube,compedit/react-youtube,troybetz/react-youtube,denisnazarov/react-youtube,danieldiekmeier/react-youtube