make the rangy.shim(iframeWin) works

[shuizhongyueming]

I want to use rangy.shim for a iframe window to make At.js work fine under IE6 with a contentEditable iframe.

with code like below

rangy.shim(ifr.contentWindow);

but when I make a Breakpoints at the code below

api.addShimListener(function(win) {
    if (typeof win.getSelection == "undefined") {
        win.getSelection = function() {
            return getSelection(win);   // at here the win is null
        };
    }
    win = null;   // set the win to null will make the returned getSelection can't get the real win
});

so I delete the win = null;

and also the doc.createRange