title: Property bluetooth does not exist on type ‘Navigator'
body: <p>I integrated <a href="https://googlechrome.github.io/samples/web-bluetooth/device-information-characteristics.html" rel="nofollow noreferrer">sample code</a> into my Angular 6 project. But there some compile errors. One of these errors is:
  Property 'bluetooth' does not exist on type 'Navigator'.</p>
  
  <p>Why this error happens and how can I solve it?</p>