New version of stream browser/ index.js

[xuxianer]

New version of stream browser/ index.js ， I use node v12.* ,it's can't find moule
it should be
Stream.Readable = require('../readable-stream/readable.js');
Stream.Writable = require('../readable-stream/writable.js');
Stream.Duplex = require('../readable-stream/duplex.js');
Stream.Transform = require('../readable-stream/transform.js');
Stream.PassThrough = require('../readable-stream/passthrough.js');
then it's OK