[Webkit-unassigned] [Bug 239579] New: [css-cascade] Some legacy properties take precedence over standard ones that appear later

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=239579

            Bug ID: 239579
           Summary: [css-cascade] Some legacy properties take precedence
                    over standard ones that appear later
           Product: WebKit
           Version: WebKit Nightly Build
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: CSS
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: obrufau at igalia.com

Try this code:

    var s = document.body.style;
    var cs = getComputedStyle(document.body);

    s.cssText = "mask-clip: content-box";
    cs.maskClip; // "content-box"
    s.cssText = "-webkit-mask-clip: initial; mask-clip: content-box";
    cs.maskClip; // "border-box"

    s.cssText = "mask-composite: exclude";
    cs.maskComposite; // "exclude"
    s.cssText = "-webkit-mask-composite: initial; mask-composite: exclude";
    cs.maskComposite; // "add"

    s.cssText = "mask-mode: alpha";
    cs.maskMode; // "alpha"
    s.cssText = "-webkit-mask: initial; mask-mode: alpha";
    cs.maskMode; // "match-source"

    s.cssText = "overflow-wrap: anywhere";
    cs.overflowWrap; // "anywhere"
    s.cssText = "word-wrap: initial; overflow-wrap: anywhere";
    cs.overflowWrap; // "normal"

    s.cssText = "text-combine-upright: all";
    cs.textCombineUpright; // "all"
    s.cssText = "-webkit-text-combine: initial; text-combine-upright: all";
    cs.textCombineUpright; // "none"

This should not happen, the legacy properties should be implemented as one of
 - Aliases
 - Shorthands
 - Deferred properties

See https://drafts.csswg.org/css-cascade-4/#aliasing

Then the last used property would take precedence, as such:

    s.cssText = "word-wrap: break-word; overflow-wrap: anywhere";
    cs.wordWrap; // "anywhere" (not "break-word"!!!)
    cs.overflowWrap; // "anywhere" (not "break-word"!!!)
    s.cssText = "overflow-wrap: anywhere; word-wrap: break-word";
    cs.wordWrap; // "break-word"
    cs.overflowWrap; // "break-word"

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