HTMLMesh: Reuse <canvas> instance

[mrdoob]

Fixes: #22093

Description

Avoid instantiating new <canvas> elements every interacting frame 😬

[Degubi]

Hi!
I was looking at HTMLMesh (for absolutely no specific reason)
I noticed that we read from the canvas cache, but we never set anything anywhere?

https://github.com/mrdoob/three.js/blob/dev/examples/jsm/interactive/HTMLMesh.js#L474

We read here, but we never set it in the else branch, I think this might be a mistake
I commented here because it was this PR that added the canvas cache
@mrdoob @Mugen87

[Mugen87]

Good catch. Indeed, I can't spot a canvases.set( element, canvas ); statement.

Would you be willing to file a PR with the fix?

[Degubi]

Sure! #24650