Optimize website to show reader view in Firefox

As the code stands in May ’20 the trigger function (isProbablyReaderable) scores only p or pre elements and div elements that contain at least one decedent br.

A slight oversimplification of the scoring heuristic is:

• For each element in [‘p’, ‘pre’, ‘div > br’]:
  • If textContent length is > 140 chars, increase score by sqrt(length - 140)
• if cumulative score > 20, return true