This rule is not used in tests and should be removed per spec.

Differential Revision: https://phabricator.services.mozilla.com/D157249

@scroll-timeline rule was removed from the spec and wpt, so it's safe to
remove this from Gecko.

Differential Revision: https://phabricator.services.mozilla.com/D157248

While looking at moving the flag around I realized that the only reason
we have FontMetricsProvider and co is because we didn't have access to
the per-document font-prefs cache. That's trivial to fix tho, so do
that and simplify the setup for font queries even more.

Differential Revision: https://phabricator.services.mozilla.com/D157589

I think it's fair to honor it, just like we honor system color keywords.

By definition if we're forcing colors currentColor can only be forced or
a system color.

Differential Revision: https://phabricator.services.mozilla.com/D157675

Starting from
https://github.com/llvm/llvm-project/commit/6c8adc505471542be38bd71d1000062daa46d7bc,
Servo_NoteExplicitHints can end up inlined in its callers via
cross-language LTO, which didn't happen before. This yields a
miscompilation in the caller, causing crashes. Until the miscompilation
is fixed, avoid the inlining.

Differential Revision: https://phabricator.services.mozilla.com/D157423

Differential Revision: https://phabricator.services.mozilla.com/D157098

Backed out 2 changesets (bug 1667090, bug 1788605) for causing Xpcshell failures on test_css-properties-db.js. CLOSED TREE

Backed out changeset cee98ae67ea4 (bug 1788605)
Backed out changeset 404e0b4bcd0f (bug 1667090)

The font-size math keyword is implemented. It behaves as a font-size: 1em
with the extra fixup due to math-level change (and other legacy MathML
attributes). After that change, the CSS for math-level / font-size: math
is behaving as per the specification, so the math-depth is turned in
nightly.

The adjusting function for font-size: math is modified so that it's
executed only if both font-size: math (otherwise the spec says no scale
should apply) and math-depth (otherwise the scale is 1 and function exists
early anyway) are set on the element. Also checking if the current node
has a scriptsizemultiplier rule applied to use MathML3's scaling is
incorrect. Instead this is changed to check if a non-default
scriptsizemultiplier is set.

Differential Revision: https://phabricator.services.mozilla.com/D91744

Differential Revision: https://phabricator.services.mozilla.com/D156805

Differential Revision: https://phabricator.services.mozilla.com/D157098

Much like we react to font-size changes on the root.

Differential Revision: https://phabricator.services.mozilla.com/D157173

This actually caught a bug in the existing selection logic.

Differential Revision: https://phabricator.services.mozilla.com/D156414

Backed out changeset 0552fd39333b (bug 1789191) for causing mochitest failures in layout/style/test/test_revert.html CLOSED TREE

This actually caught a bug in the existing selection logic.

Differential Revision: https://phabricator.services.mozilla.com/D156414

Backed out changeset 56c223bba6d6 (bug 1789191) for causing mochitest failures in layout/style/test/test_transitions_per_property.html CLOSED TREE

This actually caught a bug in the existing selection logic.

Differential Revision: https://phabricator.services.mozilla.com/D156414

Differential Revision: https://phabricator.services.mozilla.com/D156756

Bug 1789123 - Make anonymous box wrapping inside XUL boxes be similar to modern flex boxes. r=dholbert

I haven't spotted any UI regression from this, and this should generally
make the XUL -> modern flex transition easier, and simplify some
of the relevant code.

This does fix a few layout issues with emulated flexbox.

For the most part, this shouldn't change behavior without that. This
changes behavior if you have mixed inline/non-inline content in the same
XUL box (before they'd get a single item, now you'd get the flexbox /
grid behavior of one item per inline run), and multiple inline-elements
(which would become their own flex items). But I pushed a patch with
some asserts and they didn't fire on our browser mochitests, so I think
we're good.

The UA rule refactoring (removing the inherit from xul anon blocks)
shouldn't matter in practice, since we only have one item (so
box-ordinal is irrelevant) and they have overflow: visible (so
text-overflow and overflow-clip-box shouldn't have an effect).

Differential Revision: https://phabricator.services.mozilla.com/D156375

Bug 1786147 - Remove layout.css.webkit-line-clamp.enabled, and add a new pref to apply line-clamp to all BFCs. r=dholbert

It's always true, so remove it.

Add another pref to allow -webkit-line-clamp to work on all blocks
rather than just legacy -webkit-boxes, which seems something we should
try to look into, eventually.

Depends on D155181

Differential Revision: https://phabricator.services.mozilla.com/D155182

Bug 1786147 - Make -webkit-line-clamp create a block container in the appropriate situations. r=dholbert

This is a hack, sorta, similar to Chromium's:

  https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/layout/layout_object.cc;l=356;drc=312b74e385e6aba98ab31fd911238c0dc16b396c

except at computed-value rather than used-value time, because it's both
simpler to reason about and prevents lying in the computed style.

This fixes the relevant test-case, and matches closer what Chromium does,
by not creating anonymous flex items for all elements inside the
line-clamp context.

The behavior change is covered by the test changes. I had to also fix a
couple pre-existing bugs that were caught by tests, now that the
line-clamped block is the -webkit-box-styled element rather than an anonymous
flex item (and thus now had padding).

Depends on D155180

Differential Revision: https://phabricator.services.mozilla.com/D155181

Bug 1789248 - Remove @supports selector pref. r=firefox-style-system-reviewers,layout-reviewers,boris

We've shipped it for a while.

Differential Revision: https://phabricator.services.mozilla.com/D156469

Bug 1789248 - Disallow forgiving selector-parsing in @supports. r=firefox-style-system-reviewers,layout-reviewers,boris

As per spec, see https://github.com/w3c/csswg-drafts/issues/7280

Differential Revision: https://phabricator.services.mozilla.com/D156468

See https://groups.google.com/forum/#!topic/mozilla.dev.platform/BWUvjERSXUM

Differential Revision: https://phabricator.services.mozilla.com/D49285

In the past, mathvariant was cancelling the effect of legacy
fontstyle/fontweight attributes by resetting the font-style/font-weight
properties. These legacy attributes have been removed in bug 1783841,
so remove this hack from Stylo and add corresponding WPT test.

Differential Revision: https://phabricator.services.mozilla.com/D156174

MANUAL PUSH: Orange fix CLOSED TREE

No behavior change, but simplifies the following patch.

Differential Revision: https://phabricator.services.mozilla.com/D155180

Bug 1788036 - Update font-tech feature-* keywords to features-*, as per editorial fix in the spec. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D155962

The math-depth implementation is refined to take into account the
ScriptPercentScaleDown and ScriptScriptPercentScaleDown constants (if the
parent's first valid font has a MATH table) in order to calculate the
scale factor between math-deth 0 and 1, and between 0 and 2 respectively.

Behavior is unchanged if the legacy scriptsizemultiplier attribute is
specified or if no MATH table is available.

The preference layout.css.math-depth.enabled remains disabled in nightly
until the remaining bit (support for font-size: math) is implemented in
bug 1667090.

Differential Revision: https://phabricator.services.mozilla.com/D91604

Differential Revision: https://phabricator.services.mozilla.com/D155569

Adds trait ZeroNoPercent to check for values that are 0 (such as 0px) but not 0%

Updated test css/css-transforms/animation/translate-interpolation.html and removed unnecessary formatting changes

Differential Revision: https://phabricator.services.mozilla.com/D154930

This implements https://github.com/w3c/csswg-drafts/pull/7293, pending a
spec resolution, so landing test as tentative for now, but the change
makes sense.

Differential Revision: https://phabricator.services.mozilla.com/D155602

These are gated by the same layout.css.font-tech.enabled pref as the
closely-related `tech()` function for the @font-face src descriptor;
once the spec questions are settled, we should enable them all together.

Differential Revision: https://phabricator.services.mozilla.com/D155359

Backed out changeset 077219c44704 (bug 1786493)
Backed out changeset b1b0464f9bed (bug 1786493)

These are gated by the same layout.css.font-tech.enabled pref as the
closely-related `tech()` function for the @font-face src descriptor;
once the spec questions are settled, we should enable them all together.

Differential Revision: https://phabricator.services.mozilla.com/D155359

Bug 1786804 - Put the @font-face src tech() function behind a pref, enabled only on Nightly for now. r=emilio

There are a couple of current issues/discussions that may lead to a change in the set of supported keywords, so we may want to hold back a little on actually shipping this.

- In https://github.com/w3c/IFT/pull/113, the WebFonts WG proposes several new incremental-* keywords (and maybe implies dropping the currently-defined incremental?)

- In https://github.com/w3c/csswg-drafts/issues/7633, I just proposed renaming the feature-* keywords to features-* (plural) for better readability; I'd like to see a decision on that before we ship this to release.

Differential Revision: https://phabricator.services.mozilla.com/D155458

This patch will use the width/height attributes from <source> to override
width/height/aspect-ratio CSS property values of <img> elements.

So basically, we need to introduce an extra nsMappedAttribtue member in
HTMLSourceElement (and it only stores width and height attributes).
And then we use it as an extra declarations (which are generated by
Gecko_GetExtraContentStyleDeclarations()) so we can override the
declarations created from presentation attributes of <img>.

Besides, we need to make sure <img> elements get restyled in the
following cases:
1. width/height attributes is changed in <source> elements
2. <source> is inserted as a <picture>'s child
3. <source> is removed from the child list of <picture>
4. <img> is inserted as a <picture>'s child
5. <img> is removed from the child list of <picture>

We make the responsive source synchronously get updated in the previous patch,
so now we can just restyle the image when updating its responsive source.

Note: We fix the reflection of percentages for width/height attributes in
the next patch.

Differential Revision: https://phabricator.services.mozilla.com/D152586

Bug 1134171 - When serializing background shorthand skip initial values and order values according to grammar. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D155077

Fix some tests to:

 * Not assume `double` precision.
 * Account for recent working group resolution with regards to NaN: https://github.com/w3c/csswg-drafts/issues/7067#issuecomment-1111211295

Not sure I caught all, but normalizing to 0 was already our existing
behavior. This feature needs more work before it can be enabled more
generally, so make it nightly-only, for now.

Also, it's unclear per spec what the serialization for infinity*1s or so
should be. Right now we serialize to <very-big-number>s, which seems
reasonable, but some tests (but not others!) expect different behavior.

I left those untouched for now.

Differential Revision: https://phabricator.services.mozilla.com/D154883