In core.js you'll find lots of function declerations like the following:
!function(undefined){
    var __e = null, __g = null;
    // more code
}
Or this one:
!function(){
  try {
    var iter = [1].keys();
    iter['return'] = function(){ DANGER_CLOSING = false; };
    Array.from(iter, function(){ throw 2; });
  } catch(e){ /* empty */ }
}();
What is the purpose of the negation?
