Adding support for URLSearchParams

lib/helpers/buildURL.js

@@ -29,6 +29,8 @@ module.exports = function buildURL(url, params, paramsSerializer) {
   var serializedParams;
   if (paramsSerializer) {
     serializedParams = paramsSerializer(params);
+  } else if (utils.isURLSearchParams(params)) {
+    serializedParams = params.toString();
   } else {
     var parts = [];
 
@@ -64,4 +66,3 @@ module.exports = function buildURL(url, params, paramsSerializer) {
 
   return url;
 };
-

lib/helpers/normalizeHeaderName.js

@@ -0,0 +1,12 @@
+'use strict';
+
+var utils = require('../utils');
+
+module.exports = function normalizeHeaderName(headers, normalizedName) {
+  utils.forEach(headers, function processHeader(value, name) {
+    if (name !== normalizedName && name.toUpperCase() === normalizedName.toUpperCase()) {
+      headers[normalizedName] = value;
+      delete headers[name];
+    }
+  });
+};