1554168 - [wpt-sync] Sync PR 16996 - [LayoutNG] OBJECTs with fallback content may not create a new FC.

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 16996 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/16996
Details from upstream follow.

Morten Stenshorne <[e-mail]> wrote:

[LayoutNG] OBJECTs with fallback content may not create a new FC.

Avoid false positives from DefinitelyNewFormattingContext().

If an OBJECT element ends up using its fallback content, we cannot claim
that it's going to establish a new formatting context, just by looking
at the element type. Then the OBJECT behaves just like any generic
element.

Always reporting that an OBJECT establishes a new formatting context,
allowed the parent to use LayoutNG, although the OBJECT had children
(e.g. a RUBY element) that require legacy layout. Letting NG and legacy
cooperate in the same block formatting context is something we don't
support.

Bug: 966363
Change-Id: Ica9247e9936eb1dbdfc8dabdc96cdb2afdad5bac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1628711
Commit-Queue: Morten Stenshorne \<[e-mail]>
Commit-Queue: Emil A Eklund \<[e-mail]>
Auto-Submit: Morten Stenshorne \<[e-mail]>
Reviewed-by: Ian Kilpatrick \<[e-mail]>
Reviewed-by: Emil A Eklund \<[e-mail]>
Cr-Commit-Position: refs/heads/master@{#663053}

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try https://treeherder.mozilla.org/#/jobs?repo=try&revision=9cc4dcbdf90915f70843a826f8611a5a115b3749

Comment 2

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=ce460921206bba90ff401b071b08f97ec394133f

Comment 3

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Failed to get results from try push

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/393f1a7fe987
[wpt PR 16996] - [LayoutNG] OBJECTs with fallback content may not create a new FC., a=testonly

Comment 5

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/393f1a7fe987

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/393f1a7fe987