Safari doesn't set content-length when using xmlhttprequest - wcf

Question

I have a Javascript object that i am trying to post to the server with XMLHttpRequest() using JSON.stringify(). my code works fine in all major browsers except for Safari (5.1.2). My analysis shows that Safari, is in fact sending the data. i can see the message in the Safari Developer Tools and i see the bytes received in the IIS logs and it seems accurate (48kb) but the WCF function doesn't get the object data. In looking into the wcf logs i see that the content-length is 0 for safari and has a value for chrome. Does anyone have any insight to this issue?
SAFARI:
<httprequest>
<Method>POST</Method>
<QueryString></QueryString>
<WebHeaders>
<Connection>keep-alive</Connection>
<Content-Length>0</Content-Length>
<Content-Type>application/json</Content-Type>
<Accept>*/*</Accept>
<Accept-Encoding>gzip, deflate</Accept-Encoding>
<Accept-Language>en-US</Accept-Language>
<Authorization>Negotiate TlRMTVNTUA</Authorization>
<Cookie>ASP.NET_SessionId=2ynxibj2jovjo345nckpsskm</Cookie>
<Host>localhost</Host>
<Referer>http://localhost/xRMS.Net/PROFILE/Employee.htm?winid=flENz4mLt1TRBTvL&theme=ThemeDevelopment.css</Referer>
<User-Agent>Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.52.7 (KHTML, like Gecko) Version/5.1.2 Safari/534.52.7</User-Agent>
<Origin>http://localhost</Origin>
</WebHeaders>
</httprequest>
CHROME:
<httprequest>
<Method>POST</Method>
<QueryString></QueryString>
<WebHeaders>
<Connection>keep-alive</Connection>
<Content-Length>48822</Content-Length>
<Content-Type>application/json</Content-Type>
<Accept>*/*</Accept>
<Accept-Charset>ISO-8859-1,utf-8;q=0.7,*;q=0.3</Accept-Charset>
<Accept-Encoding>gzip,deflate,sdch</Accept-Encoding>
<Accept-Language>en-US,en;q=0.8</Accept-Language>
<Cookie>ASP.NET_SessionId=gapksa2mmuh3wcrntz32mipw</Cookie>
<Host>localhost</Host>
<Referer>http://localhost/xRMS.Net/PROFILE/Employee.htm?winid=FTWLXL4b8aTWaaaM&theme=ThemeDevelopment.css</Referer>
<User-Agent>Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2</User-Agent>
<Origin>http://localhost</Origin>
</WebHeaders>
</httprequest>