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>

test/specs/cancel/CancelToken.spec.js

@@ -1,5 +1,5 @@
-var CancelToken = require('../../../lib/cancel/CancelToken');
-var CanceledError = require('../../../lib/cancel/CanceledError');
+import CancelToken from '../../../lib/cancel/CancelToken';
+import CanceledError from '../../../lib/cancel/CanceledError';
 
 describe('CancelToken', function() {
   describe('constructor', function() {
@@ -18,8 +18,8 @@ describe('CancelToken', function() {
 
   describe('reason', function() {
     it('returns a CanceledError if cancellation has been requested', function() {
-      var cancel;
-      var token = new CancelToken(function(c) {
+      let cancel;
+      const token = new CancelToken(function(c) {
         cancel = c;
       });
       cancel('Operation has been canceled.');
@@ -28,15 +28,15 @@ describe('CancelToken', function() {
     });
 
     it('returns undefined if cancellation has not been requested', function() {
-      var token = new CancelToken(function() {});
+      const token = new CancelToken(function() {});
       expect(token.reason).toBeUndefined();
     });
   });
 
   describe('promise', function() {
     it('returns a Promise that resolves when cancellation is requested', function(done) {
-      var cancel;
-      var token = new CancelToken(function(c) {
+      let cancel;
+      const token = new CancelToken(function(c) {
         cancel = c;
       });
       token.promise.then(function onFulfilled(value) {
@@ -51,8 +51,8 @@ describe('CancelToken', function() {
   describe('throwIfRequested', function() {
     it('throws if cancellation has been requested', function() {
       // Note: we cannot use expect.toThrowError here as CanceledError does not inherit from Error
-      var cancel;
-      var token = new CancelToken(function(c) {
+      let cancel;
+      const token = new CancelToken(function(c) {
         cancel = c;
       });
       cancel('Operation has been canceled.');
@@ -68,14 +68,14 @@ describe('CancelToken', function() {
     });
 
     it('does not throw if cancellation has not been requested', function() {
-      var token = new CancelToken(function() {});
+      const token = new CancelToken(function() {});
       token.throwIfRequested();
     });
   });
 
   describe('source', function() {
     it('returns an object containing token and cancel function', function() {
-      var source = CancelToken.source();
+      const source = CancelToken.source();
       expect(source.token).toEqual(jasmine.any(CancelToken));
       expect(source.cancel).toEqual(jasmine.any(Function));
       expect(source.token.reason).toBeUndefined();

test/specs/cancel/CanceledError.spec.js

@@ -1,14 +1,14 @@
-var CanceledError = require('../../../lib/cancel/CanceledError');
+import CanceledError from '../../../lib/cancel/CanceledError';
 
 describe('Cancel', function() {
   describe('toString', function() {
     it('returns correct result when message is not specified', function() {
-      var cancel = new CanceledError();
+      const cancel = new CanceledError();
       expect(cancel.toString()).toBe('CanceledError: canceled');
     });
 
     it('returns correct result when message is specified', function() {
-      var cancel = new CanceledError('Operation has been canceled.');
+      const cancel = new CanceledError('Operation has been canceled.');
       expect(cancel.toString()).toBe('CanceledError: Operation has been canceled.');
     });
   });

test/specs/cancel/isCancel.spec.js

@@ -1,5 +1,5 @@
-var isCancel = require('../../../lib/cancel/isCancel');
-var CanceledError = require('../../../lib/cancel/CanceledError');
+import isCancel from '../../../lib/cancel/isCancel';
+import CanceledError from '../../../lib/cancel/CanceledError';
 
 describe('isCancel', function() {
   it('returns true if value is a CanceledError', function() {