Closed Bug 1452283 Opened 5 years ago Closed 5 years ago

[wpt-sync] Sync PR 10304 - Out-of-flow descendants may still be part of the flow thread.


(Core :: CSS Parsing and Computation, enhancement, P4)




Tracking Status
firefox61 --- fixed


(Reporter:, Unassigned)




(Whiteboard: [wptsync downstream])

Sync web-platform-tests PR 10304 into mozilla-central (this bug is closed when the sync is complete).

Details from upstream follow.

Morten Stenshorne <> wrote:
>  Out-of-flow descendants may still be part of the flow thread.
>  When changing a layout object from in-flow to out-of-flow positioned, we
>  used to just remove it from the flow thread, risking that there'd no
>  longer be a column set to associate it with. However, an out-of-flow
>  positioned descendant may be contained by something that's inside the
>  flow thread, e.g. if the containing block of an absolutely positioned
>  object is a relatively positioned object, and that relatively positioned
>  object is contained by the flow thread.
>  Since it's hard to detect what the new containing block of an object is
>  going to be before it has actually gone out of flow, we'll still remove
>  it from the flow thread, but we'll now detect that we need to re-insert
>  it when computed style has updated.
>  Bug: 827424
>  Change-Id: I413348b0d3ecd0c4b5051e6e9d2a4526863bef60
>  Reviewed-on:
>  Reviewed-by: Emil A Eklund <>
>  Commit-Queue: Morten Stenshorne <>
>  Cr-Commit-Position: refs/heads/master@{#548354}
Component: web-platform-tests → CSS Parsing and Computation
Product: Testing → Core
Ran 1 tests and 1 subtests
OK     : 1
PASS   : 1
Pushed by
[wpt PR 10304] - Out-of-flow descendants may still be part of the flow thread., a=testonly
Closed: 5 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla61
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