layout: Use overflow: visible if overflow was propagated to viewport (#38598)

The `overflow-*` values of either the root element or the `<body>` get
propagated to the viewport. However, we were missing this part:
> The element from which the value is propagated must then have a used
`overflow` value of `visible`.

See https://drafts.csswg.org/css-overflow/#overflow-propagation

Testing:
 - `css/cssom-view/scrolling-quirks-vs-nonquirks.html`
 - `css/css-overflow/overflow-body-propagation-007.html`
 - `css/css-overflow/overflow-body-propagation-008.html`
 - `css/css-overflow/overflow-body-propagation-009.html`
 - `css/css-overflow/scrollable-overflow-with-nested-elements-001.html` 
 - `css/css-overflow/scrollable-overflow-with-nested-elements-002.html` 
 - `css/css-overflow/scrollable-overflow-with-nested-elements-003.html`
 - `css/css-overflow/scrollable-overflow-with-nested-elements-004.html`
 - `css/css-overflow/scrollbar-gutter-scroll-into-view.html`

Failures:
 - `css/css-overflow/overflow-body-propagation-010.html`
   Failing because of missing support for `contain: paint`.
- `css/css-overflow/scrollable-overflow-with-nested-elements-005.html`
Failing because of wrong `data-expected-height`, but correct
`data-expected-scroll-height` which is core of this PR.
`data-expected-height` can be dealt separately.


Fixes: #38248

---------

Signed-off-by: Shubham Gupta <shubham13297@gmail.com>
Signed-off-by: Oriol Brufau <obrufau@igalia.com>
Co-authored-by: Oriol Brufau <obrufau@igalia.com>
This commit is contained in:
Shubham Gupta 2025-08-20 22:21:51 +08:00 committed by GitHub
parent 37088aa4c3
commit d8ff9c7a08
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22 changed files with 373 additions and 72 deletions

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@ -176,6 +176,9 @@ bitflags! {
const SIZE_DEPENDS_ON_BLOCK_CONSTRAINTS_AND_CAN_BE_CHILD_OF_FLEX_ITEM = 1 << 8;
/// Whether or not the node that created this fragment is the root element.
const IS_ROOT_ELEMENT = 1 << 9;
/// If element has propagated the overflow value to viewport.
const PROPAGATED_OVERFLOW_TO_VIEWPORT = 1 << 10;
}
}