• Operating System version: Win10 64bit
• Browser version: Chrome 71
• Firebase SDK version: 5.5.8 & 5.7.0
• Firebase Product: firebase-app

Make an html file with boilerplate, and in head:

1. Load these scripts: firebase-app.js & firebase-auth.js
2. Put this in a script with your project infos:

firebase.initializeApp( {
	apiKey: '...',
	authDomain: '...',
	databaseURL: '...',
	projectId: '...',
	storageBucket: '...',
	messagingSenderId: '...'
})

3. Open html file in Chrome and open devTools -> performance monitor
   see the number of event listeners constantly rise until garbage collection.