2011021 - [wpt-sync] Sync PR 56691 - Map `placeholder` and `placeholder-shown` web-features

Status: NEW

(Testing :: web-platform-tests, task, P4)

Description

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

Sync web-platform-tests PR 56691 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/56691
Details from upstream follow.

Stalgia Grigg <[e-mail]> wrote:

Map placeholder and placeholder-shown web-features

Feature: placeholder
Reference: https://github.com/web-platform-dx/web-features/blob/main/features/placeholder.yml

Feature: placeholder-shown
Reference: https://github.com/web-platform-dx/web-features/blob/main/features/placeholder-shown.yml

Hello, reviewers! As of 2025-12-05, the wpt-pr-bot is requesting reviews from code owners for changes to WEB_FEATURES.yml files. To learn more about the purpose of these files, check out this presentation from TPAC 2025, Annotating WPT to Surface the Status of the Platform.

Notable exclusions

1. Interaction tests primarily about other features

   • css/css-shadow-parts/interaction-with-pseudo-elements.html (shadow-parts)
   • css/css-shadow-parts/pseudo-*-after-part.html (shadow-parts)
   • css/selectors/invalidation/input-pseudo-classes-in-has.html (has)
   • css/css-pseudo/first-line-and-placeholder.html (mapped to first-line)
   • html/rendering/non-replaced-elements/form-controls/input-placeholder-line-height.html: Verifies line-height has no effect on placeholders, on the fence about whether this falls under line-height or placeholder but went with exclusion
   • html/rendering/replaced-elements/attributes-for-embedded-content-and-images/number-placeholder-right-aligned.html: Verifies placeholder text positioning respects input alignment, again on the fence but went with exclusion

2. Tests about field-sizing using placeholder as context

   • html/rendering/widgets/field-sizing-placeholder-stretch.html
   • html/rendering/widgets/field-sizing-*.html

3. Tests about general pseudo-element parsing

   • css/css-pseudo/parsing/tree-abiding-pseudo-elements.html
   • css/cssom/getComputedStyle-pseudo.html