proposal: `unlike-to-change` : hinting the opposite meaning as `will-change` does

[Zhang-Junzhi]

The real-world use case is: most of time, most of the property values on document elements are defined constant(I.e. not possible to be changed by any ways).

As well as hinting what will soon be changed, I think it's also reasonable to add ability of providing a rendering hint(unlike-to-change) to the user agent that what is very unlikely or (usually) impossible to be changed, so that a UA can optimise the styling in the cost of slowing performance for changing the value, even if it would be a noticeable lagging, since it's almost impossible to be changed, who cares?

[Zhang-Junzhi]

Oftentimes, all properties on an element aren't possible to be changed.

So the custom-ident all can be treated specially as all properties, not the all itself.