Allow for Buffer instances as request bodies

Author: jbpros

lib/XMLHttpRequest.js

@@ -344,7 +344,7 @@ exports.XMLHttpRequest = function() {
     if (settings.method === "GET" || settings.method === "HEAD") {
       data = null;
     } else if (data) {
-      headers["Content-Length"] = Buffer.byteLength(data);
+      headers["Content-Length"] = Buffer.isBuffer(data) ? data.length : Buffer.byteLength(data);
 
       if (!headers["Content-Type"]) {
         headers["Content-Type"] = "text/plain;charset=UTF-8";