function installPostMessageImplementation() {
// Installs an event handler on `global` for the `message` event: see
// * https://developer.mozilla.org/en/DOM/window.postMessage
// * http://www.whatwg.org/specs/web-apps/current-work/multipage/comms.html#crossDocumentMessages
var messagePrefix = "setImmediate$" + Math.random() + "$";
var onGlobalMessage = function(event) {
if (event.source === global &&
typeof event.data === "string" &&
event.data.indexOf(messagePrefix) === 0) {
runIfPresent(+event.data.slice(messagePrefix.length));
}
};
if (global.addEventListener) {
global.addEventListener("message", onGlobalMessage, false);
} else {
global.attachEvent("onmessage", onGlobalMessage);
}
setImmediate = function() {
var handle = addFromSetImmediateArguments(arguments);
global.postMessage(messagePrefix + handle, "*");
return handle;
};
}
if (xobject) {
delete Request.requests[this.index];
}
this.xhr = null;
};
/**
* Aborts the request.
*
* @api public
*/
Request.prototype.abort = function(){
this.cleanup();
};
if (xobject) {
Request.requestsCount = 0;
Request.requests = {};
global.attachEvent('onunload', function(){
for (var i in Request.requests) {
if (Request.requests.hasOwnProperty(i)) {
Request.requests[i].abort();
}
}
});
}