(function() {
    /* patch MS AJAX to support webkit browsers */
    function patchMicrosoftAjax() {
        Sys.Browser = {};
        Sys.Browser.InternetExplorer = {};
        Sys.Browser.Firefox = {};
        Sys.Browser.WebKit = {}; //Safari 3 is considered WebKit 
        Sys.Browser.Safari = {};
        Sys.Browser.Opera = {};
        Sys.Browser.agent = null;
        Sys.Browser.hasDebuggerStatement = false;
        Sys.Browser.name = navigator.appName;
        Sys.Browser.version = parseFloat(navigator.appVersion);
        if (navigator.userAgent.indexOf(' MSIE ') > -1) {
            Sys.Browser.agent = Sys.Browser.InternetExplorer;
            Sys.Browser.version = parseFloat(navigator.userAgent.match(/MSIE (\d+\.\d+)/)[1]);
            Sys.Browser.hasDebuggerStatement = true;
        } else if (navigator.userAgent.indexOf(' Firefox/') > -1) {
            Sys.Browser.agent = Sys.Browser.Firefox;
            Sys.Browser.version = parseFloat(navigator.userAgent.match(/ Firefox\/(\d+\.\d+)/)[1]);
            Sys.Browser.name = 'Firefox';
            Sys.Browser.hasDebuggerStatement = true;
        } else if (navigator.userAgent.indexOf('WebKit/') > -1) {
            Sys.Browser.agent = Sys.Browser.WebKit;
            Sys.Browser.version = parseFloat(navigator.userAgent.match(/WebKit\/(\d+(\.\d+)?)/)[1]);
            Sys.Browser.name = 'WebKit';
        } else if (navigator.userAgent.indexOf(' Safari/') > -1) {
            Sys.Browser.agent = Sys.Browser.Safari;
            Sys.Browser.version = parseFloat(navigator.userAgent.match(/ Safari\/(\d+(\.\d+)?)/)[1]);
            Sys.Browser.name = 'Safari';
        } else if (navigator.userAgent.indexOf('Opera/') > -1) {
            Sys.Browser.agent = Sys.Browser.Opera;
        }
    }
    if (jQuery) jQuery(patchMicrosoftAjax);
})();

http://blogs.prakashinfotech.com/Lists/Posts/Post.aspx?ID=24

Load this Javascript after the MS AJAX files have been loaded.  In the example I am using jQuery to call the patchMicrosoftAjax() method, but you can use any method you desire.

ASP.net & MS AJAX: Enabling WebKit support (chrome, safari) in MS AJAX (fixing webkit browser detection)

ajax, javascript, aspnet

JavaScript