Accept-Charset httpHeader Issue with Firefox and Chrome

[bill78b]

I am trying to Pass httpHeaders to Request..
I am facing issue regarding Accept-Charset httpHeader...

dataURL: "../erl",
recordXPath: "//componentlayout",
requestProperties: {
httpHeaders: {
"Accept": "application/vnd.ptc.sclayout+xml;version=1",
"Accept-Charset": "UTF-8"
}
}

this code is working in IE9 .... but not in firefox and chrome...

Accept-Charset is setting in IE9...

Accept-Charset is not setting in Firefox and Chrome...

Any thoughts....