Bug 240341 – Turn legacy properties that share a computed style into aliases or shorthands

• Status: RESOLVED
• Resolution: FIXED
• Component: CSS

[Oriol Brufau]

Currently, there are 8 pairs of properties that share a computed style:

 * background-clip, -webkit-background-clip
 * background-origin, -webkit-background-origin
 * background-size, -webkit-background-size
 * box-shadow, -webkit-box-shadow
 * mask-clip, -webkit-mask-clip
 * mask-composite, -webkit-mask-composite
 * mask-mode, -webkit-mask-source-type
 * text-combine-upright, -webkit-text-combine

This is a non-standard hack. CSS Cascade defines 2 standard ways: https://www.w3.org/TR/css-cascade-5/#aliasing
 * legacy name aliases, for properties with the same exact syntax
 * legacy shorthands, for properties with different syntax

So the -webkit- properties above should be turned into aliases or shorthands.

The current hack is more likely to break things, e.g. revert-layer was broken before bug 238125, and CSSOM is still broken (bug 238874).

[Tim Nguyen (:ntim)]

Bug 104805 is an example of legacy shorthand.

[Radar WebKit Bug Importer]

<rdar://problem/93572921>

[Oriol Brufau]

This has been done, see bug 277623 comment 0

> The "related-property" mechanism has no clients left