根据标准，哪个JS函数声明语法是正确的？

  var foo = function(){ return 1; };
  if (true) {
    function foo(){ return 2; }
  }
  foo(); // 1 in Chrome // 2 in FF
  //I just want to be sure, is FF 4 not "standard" in this case?
  var foo = function(){ return 1; };
  if (true