Axios ES2017 (#4787)

* Added AxiosHeaders class;

* Fixed README.md href;

* Fixed a potential bug with headers normalization;

* Fixed a potential bug with headers normalization;
Refactored accessor building routine;
Refactored default transforms;
Removed `normalizeHeaderName` helper;

* Added `Content-Length` accessor;
Added missed `has` accessor to TS types;

* Added `AxiosTransformStream` class;
Added progress capturing ability for node.js environment;
Added `maxRate` option to limit the data rate in node.js environment;
Refactored event handled by `onUploadProgress` && `onDownloadProgress` listeners in browser environment;
Added progress & data rate tests for the http adapter;
Added response stream aborting test;
Added a manual progress capture test for the browser;
Updated TS types;
Added TS tests;
Refactored request abort logic for the http adapter;
Added ability to abort the response stream;

* Remove `stream/promises` & `timers/promises` modules usage in tests;

* Use `abortcontroller-polyfill`;

* Fixed AxiosTransformStream dead-lock in legacy node versions;
Fixed CancelError emitting in streams;

* Reworked AxiosTransformStream internal logic to optimize memory consumption;
Added throwing an error if the request stream was silently destroying (without error) Refers to #3966;

* Treat the destruction of the request stream as a cancellation of the request;
Fixed tests;

* Emit `progress` event in the next tick;

* Initial refactoring;

* Refactored Mocha tests to use ESM;

* Refactored Karma tests to use rollup preprocessor & ESM;
Replaced grunt with gulp;
Improved dev scripts;
Added Babel for rollup build;

* Added default commonjs package export for Node build;
Added automatic contributors list generator for package.json;

Co-authored-by: Jay <jasonsaayman@gmail.com>

lib/core/dispatchRequest.js

@@ -1,11 +1,10 @@
 'use strict';
 
-var utils = require('./../utils');
-var transformData = require('./transformData');
-var isCancel = require('../cancel/isCancel');
-var defaults = require('../defaults');
-var CanceledError = require('../cancel/CanceledError');
-var normalizeHeaderName = require('../helpers/normalizeHeaderName');
+import transformData from './transformData.js';
+import isCancel from '../cancel/isCancel.js';
+import defaults from '../defaults/index.js';
+import CanceledError from '../cancel/CanceledError.js';
+import AxiosHeaders from '../core/AxiosHeaders.js';
 
 /**
  * Throws a `CanceledError` if cancellation has been requested.
@@ -31,39 +30,18 @@ function throwIfCancellationRequested(config) {
  *
  * @returns {Promise} The Promise to be fulfilled
  */
-module.exports = function dispatchRequest(config) {
+export default function dispatchRequest(config) {
   throwIfCancellationRequested(config);
 
-  // Ensure headers exist
-  config.headers = config.headers || {};
+  config.headers = AxiosHeaders.from(config.headers);
 
   // Transform request data
   config.data = transformData.call(
     config,
-    config.data,
-    config.headers,
-    null,
     config.transformRequest
   );
 
-  normalizeHeaderName(config.headers, 'Accept');
-  normalizeHeaderName(config.headers, 'Content-Type');
-
-  // Flatten headers
-  config.headers = utils.merge(
-    config.headers.common || {},
-    config.headers[config.method] || {},
-    config.headers
-  );
-
-  utils.forEach(
-    ['delete', 'get', 'head', 'post', 'put', 'patch', 'common'],
-    function cleanHeaderConfig(method) {
-      delete config.headers[method];
-    }
-  );
-
-  var adapter = config.adapter || defaults.adapter;
+  const adapter = config.adapter || defaults.adapter;
 
   return adapter(config).then(function onAdapterResolution(response) {
     throwIfCancellationRequested(config);
@@ -71,12 +49,12 @@ module.exports = function dispatchRequest(config) {
     // Transform response data
     response.data = transformData.call(
       config,
-      response.data,
-      response.headers,
-      response.status,
-      config.transformResponse
+      config.transformResponse,
+      response
     );
 
+    response.headers = AxiosHeaders.from(response.headers);
+
     return response;
   }, function onAdapterRejection(reason) {
     if (!isCancel(reason)) {
@@ -86,14 +64,13 @@ module.exports = function dispatchRequest(config) {
       if (reason && reason.response) {
         reason.response.data = transformData.call(
           config,
-          reason.response.data,
-          reason.response.headers,
-          reason.response.status,
-          config.transformResponse
+          config.transformResponse,
+          reason.response
         );
+        reason.response.headers = AxiosHeaders.from(reason.response.headers);
       }
     }
 
     return Promise.reject(reason);
   });
-};
+}