code: function fill(obj, name, replacement, track) {
  	  if (obj == null) return;
  	  var orig = obj[name];
  	  obj[name] = replacement(orig);
  	  obj[name].__raven__ = true;
  	  obj[name].__orig__ = orig;
  
  	  if (track) {
  	    track.push([obj, name, orig]);
  	  }
  	}
docs: Polyfill a method
  @param obj object e.g. `document`
  @param name method name present on object e.g. `addEventListener`
  @param replacement replacement function
  @param track {optional} record instrumentation to an array