fix(browser): enable 'bdd' import for bundlers (mochajs#4769)

browser-entry.js

@@ -209,8 +209,18 @@ Mocha.process = process;
 /**
  * Expose mocha.
  */
-
 global.Mocha = Mocha;
 global.mocha = mocha;
 
+// for bundlers: enable `import {describe, it} from 'mocha'`
+// `bdd` interface only
+// prettier-ignore
+[ 
+  'describe', 'context', 'it', 'specify',
+  'xdescribe', 'xcontext', 'xit', 'xspecify',
+  'before', 'beforeEach', 'afterEach', 'after'
+].forEach(function(key) {
+  mocha[key] = global[key];
+});
+
 module.exports = mocha;

test/browser-specific/setup.js

@@ -8,5 +8,3 @@ global.expect = require('unexpected')
   .use(require('unexpected-map'))
   .use(require('unexpected-sinon'))
   .use(require('unexpected-eventemitter'));
-
-require('../../browser-entry');

test/unit/required-tokens.spec.js

@@ -0,0 +1,11 @@
+'use strict';
+
+const assert = require('assert');
+const {describe, it} = require('../..');
+
+describe('using imported "describe"', function() {
+  it('using imported "it"', function(done) {
+    assert.ok(true);
+    done();
+  });
+});