Websocket Provider's btoa helper's context [browser only]

[vsleibenko]

Expected behavior

I can connect via Websocket Provider using url with credentials 'wss://USERNAME:PASSWORD@WSS_ENDPOINT'

Actual behavior

Received TypeError: Illegal invocation

Seems like 'btoa' this isn't pointing to Window object as it should but to WebsocketProvider's object

NOTE: Binding 'btoa' to Window object in 'helpers.js' solves the issue
_btoa = btoa.bind(window); (web3-providers-ws/src/helpers.js:21)
Locking context with arrow function also works
_btoa = (str) => btoa(str); (web3-providers-ws/src/helpers.js:21)

Steps to reproduce the behavior

1. Try to connect to url type of 'wss://USERNAME:PASSWORD@WSS_ENDPOINT' using WebsocketProvider (web version)

Logs

TypeError: Illegal invocation
new WebsocketProvider
node_modules/web3-providers-ws/src/index.js:73

70 | var parsedURL = helpers.parseURL(url);
71 |
72 | if (parsedURL.username && parsedURL.password) {
73 | this.headers.authorization = 'Basic ' + helpers.btoa(parsedURL.username + ':' + parsedURL.password);

Environment

web3.js: 1.2.7
Chrome: 81.0
OS: MacOS Catalina (10.15.4 )