Allow to target an element of the page

[Aarbel]

The inspector doesn't work for public websites because they don't often set window.scene = scene and window.THREE = THREE.

Could be great to inspect any Three.js canvas of any webpage.
Example : https://sketchfab.com/models/de3333192eb4436896d2b8500cff531a

@jeromeetienne what do you think about that ?