title: firefox spamming ondragenter event
body: <p>Trying to build some drag'n'drop functionality and got a weird bug in Firefox. I have the whole document's body as a drop zone and want to change <code>h1</code> value when some object is being dragged over the page. </p>
  
  <p>Seems like no problem at all: <a href="http://jsfiddle.net/j7u6hLyj/" rel="nofollow">http://jsfiddle.net/j7u6hLyj/</a></p>
  
  <p>It works as it should everywhere, except Firefox. When I'm dragging an object through the page - it's no problem, except the situation when the object is being dragged over the text, if you'd try the example and drag a file over the text you would notice that <code>ondragenter</code> event is being fired non-stop while the object is floating over the text. It happens only in Firefox.</p>