The client-side model of the input text control does not currently provide support for a mask. However, there are certainly many 3rd party javascript libraries that can do something like that or you can probably accomplish it with your own custom javascript code in the keyup client-side event handler of the text input control.
For example, something like this as the keyup client-side event handler:
var v = this.value;
if (v.match(/^\d{2}$/) !== null) {
this.value = v + '/';
} else if (v.match(/^\d{2}\/\d{2}$/) !== null) {
this.value = v + '/';
}