strange dead code elimination output

[bronze1man]

I have all done the test with http://babeljs.io/repl it says babel 6.x

input :

(function(){
  // not call function, should delete.
  function nfn1(){
    console.log("not use1");
  }
  // not use object ,should delete.
  var nobj = {};
  // not call function, should delete.
  nobj.m = function(){
    console.log("not use2");
  }
  var flag = false;
  if (flag==true){
  	console.log("not use3");
  }
  function kNew(){
    return {};
  }
  var gObj = null;
  function kGetDefault(){
    if (gObj === null){
		gObj = kNew();
	}
	return gObj;
  }
  function kSetDefault(ke){
    gObj = ke;
  }
  // /////////
  // should remain test:
  function uobj(){
    console.log("use 3");
  }
  // export api,must in the source code.
  window["abc"] = function(){
    console.log("use 1");
  }
  // direct run code, must in the output code
  console.log("use 2");
  uobj();

})();

output:

(function() {
  var h = null;
  (window.abc = function() {
    console.log("use 1");
  }),
    console.log("use 2"),
    (function() {
      console.log("use 3");
    })();
})();

What is the var h = null; stuff?

[bardiharborow]

Reduced Test Case

Input:

(function(){
  var gObj = null;
  function kGetDefault() {
    if (gObj === null) {
      gObj = kNew();
    }
  }
})();

Output:

(function(){var b=null})();

There's no specification violation here, but the gObj variable could be optimized away as an enhancement (probably extra dead-code passes would be needed).