From the manual it is said that application.quit does not stop the web player or editor
How can I stop a game and return to a web page?
Application.Quit
static function Quit () : void
Description
Quits the player application. Quit is ignored in the editor or the web player.
// Quits the player when the user hits escape
function Update () {
if (Input.GetKey (“escape”)) {
Application.Quit();
}
}