winjs update context wrapper

app.js

// knockout mapping

        UpdateContext.Execute(function(){
            ko.applyBindings(viewmodel);
            viewmodel.load();
        });

WinJSAdapter.js

(function (){
    var UpdateContext = window.UpdateContext = window.UpdateContext || {};

    var isWinJS = typeof(MSApp) != 'undefined';

    if(isWinJS){
        UpdateContext.Execute = function(cb){
            MSApp.execUnsafeLocalFunction(cb);
        };
    }else{
        UpdateContext.Execute = function(cb){
            cb.call();
        };
    }
})();