[CSSWG][css-overflow-3] Updated WD of CSS Overflow L3

The CSS WG has published an updated Working Draft of the
CSS Overflow Module Level 3

     https://www.w3.org/TR/css-overflow-3/

This module contains the features of CSS relating to scrollable overflow handling in visual media.

Major changes since the previous draft include
   * Deferring all features other than the overflow/overflow-x/overflow-y
     properties themselves to Level 4
   * Filling out more details on how overflow is calculated
   * Better cross-linking

We are especially looking for close review of this section:
   https://www.w3.org/TR/css-overflow-3/#scrollable
specifically
   * Whether the description of the interaction with transforms is accurate
   * Considerations/compat data wrt honoring or ignoring 'clip' and/or 'clip-path'
   * Considerations wrt including padding and margin spacing in the scrollable
     overflow region

We are hoping to wrap this up over the summer and send it to CR,
since it is a very belated specification for something that has
been shipping in browsers since IE5. Tab and I are also hoping
that the resulting specification will be something relatively
sane. :)

Features like 'overflow: paged' and fragmented overflow are still
considered important and useful, but will be pursued in Level 4.

Please review the draft, and send any comments to this mailing list,
<[email protected]>, prefixed with [css-overflow-3] (as I did on this
message) or (preferably) file them in the GitHub repository at
   https://github.com/w3c/csswg-drafts/issues

For the CSS WG,
~fantasai