Add former paged overflow impls to prior art for Overflow Extensions Explainer

[lilles]

Both Presto and WebKit had an implementation for paged overflow for elements via prefixed values for the overflow property.

The Blink implementation was removed in Chrome 75 with this motivation:

"For developers who wish to have fragmented content, a more standardized way to do this is with multi-column:

See the previous example using this technique:
https://jsbin.com/vovelabewe/edit?html,output

For developers wishing to establish a new formatting context (to prevent margin-collapsing or similar), display: flow-root, or overflow: hidden both work.

This feature isn't widely used, and maintaining it indefinitely will likely result it a maintenance burden."

[flackr]

Thanks for the information! This technique might give the necessary utility. The paged thing bring proposed would be roughly this with implicit sizing which it seems like can be achieved by making the scroller also a container and using a container query: https://jsbin.com/modewaj/edit?html,output

There's still a need to style the fragments, most importantly applying scroll snap. It seems like right now styling is limited to the set of column- properties so we could propose either adding column-snap-align and see how far this gets us. The more general approach would be having a pseudoclass for them.

In the explainer we called this pages, as that name makes ergonomic sense, but as you've pointed out what's being asked for is really just container-sized columns.

[bkardell]

Shouldn't css regions be called out in priors too then?