Implement visibility listening through Intersection Observer API

[string-areeb]

https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API

The Intersection Observer API provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element or with a top-level document's viewport.

It is much more efficient and its polyfill is very simple for browsers which do not support it that its code is already in this library

[chrishurlburt]

@string-areeb I would happily merge any PR that implements this 😄

[string-areeb]

Thanks. Will try to implement it in a few days