add xDomainRequest adapter

lib/adapters/xhr.js

@@ -27,18 +27,30 @@ module.exports = function xhrAdapter(resolve, reject, config) {
     delete requestHeaders['Content-Type']; // Let the browser set it
   }
 
+  var adapter = (XMLHttpRequest || ActiveXObject), 
+      loadEvent = 'onreadystatechange', 
+      xDomain = false;
+
+  // For IE 8/9 CORS support
+  if(config.xDomain && (window && window.XDomainRequest)){
+    adapter = window.XDomainRequest;
+    loadEvent = 'onload';
+    xDomain = true;
+  }
+
   // Create the request
-  var request = new (XMLHttpRequest || ActiveXObject)('Microsoft.XMLHTTP');
+  var request = new adapter('Microsoft.XMLHTTP');
+
   request.open(config.method.toUpperCase(), buildUrl(config.url, config.params, config.paramsSerializer), true);
 
   // Set the request timeout in MS
   request.timeout = config.timeout;
 
   // Listen for ready state
-  request.onreadystatechange = function () {
-    if (request && request.readyState === 4) {
+  request[loadEvent] = function () {
+    if (request && (request.readyState === 4 || xDomain)) {
       // Prepare the response
-      var responseHeaders = parseHeaders(request.getAllResponseHeaders());
+      var responseHeaders = xDomain ? null : parseHeaders(request.getAllResponseHeaders());
       var responseData = ['text', ''].indexOf(config.responseType || '') !== -1 ? request.responseText : request.response;
       var response = {
         data: transformData(
@@ -51,9 +63,8 @@ module.exports = function xhrAdapter(resolve, reject, config) {
         headers: responseHeaders,
         config: config
       };
-
       // Resolve or reject the Promise based on the status
-      (request.status >= 200 && request.status < 300 ?
+      ((request.status >= 200 && request.status < 300) || (request.responseText && xDomain) ?
         resolve :
         reject)(response);
 
@@ -80,16 +91,17 @@ module.exports = function xhrAdapter(resolve, reject, config) {
   }
 
   // Add headers to the request
-  utils.forEach(requestHeaders, function (val, key) {
-    // Remove Content-Type if data is undefined
-    if (!data && key.toLowerCase() === 'content-type') {
-      delete requestHeaders[key];
-    }
-    // Otherwise add header to the request
-    else {
-      request.setRequestHeader(key, val);
-    }
-  });
+  if(!xDomain)
+    utils.forEach(requestHeaders, function (val, key) {
+      // Remove Content-Type if data is undefined
+      if (!data && key.toLowerCase() === 'content-type') {
+        delete requestHeaders[key];
+      }
+      // Otherwise add header to the request
+      else {
+        request.setRequestHeader(key, val);
+      }
+    });
 
   // Add withCredentials to request if needed
   if (config.withCredentials) {

lib/axios.js

@@ -5,6 +5,8 @@ var utils = require('./utils');
 var dispatchRequest = require('./core/dispatchRequest');
 var InterceptorManager = require('./core/InterceptorManager');
 
+require('es6-promise').polyfill();
+
 function Axios (defaultConfig) {
   this.defaultConfig = utils.merge({
     headers: {},