Implement `animation-fill-mode`

[mrobinson]

Fixes #26460.

---

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• There are tests for these changes

[highfive]

Heads up! This PR modifies the following files:

• @emilio: components/style/animation.rs, components/style/matching.rs

[mrobinson]

Note: There is a set of small manual tests in web-platform-tests, but I've added an automated test using Servo's testing time warp functionality.

[mrobinson]

@bors-servo r=jdm,emilio

[bors-servo]

📌 Commit ea58eeb has been approved by jdm,emilio

[bors-servo]

⌛ Testing commit ea58eeb with merge 9ccf667...

[bors-servo]

💔 Test failed - status-taskcluster

[CYBAI]

Failed in Linux:

error[E0433]: failed to resolve: could not find `animation_fill_mode` in `longhands`
  --> components/style/animation.rs:16:35
   |
16 | use crate::properties::longhands::animation_fill_mode::computed_value::single_value::T as AnimationFillMode;
   |                                   ^^^^^^^^^^^^^^^^^^^ could not find `animation_fill_mode` in `longhands`
error[E0433]: failed to resolve: use of undeclared type or module `AnimationFillMode`
   --> components/style/animation.rs:385:31
    |
385 |             self.fill_mode != AnimationFillMode::Backwards &&
    |                               ^^^^^^^^^^^^^^^^^ use of undeclared type or module `AnimationFillMode`
error[E0433]: failed to resolve: use of undeclared type or module `AnimationFillMode`
   --> components/style/animation.rs:386:31
    |
386 |             self.fill_mode != AnimationFillMode::Both
    |                               ^^^^^^^^^^^^^^^^^ use of undeclared type or module `AnimationFillMode`
error[E0433]: failed to resolve: use of undeclared type or module `AnimationFillMode`
   --> components/style/animation.rs:392:31
    |
392 |             self.fill_mode != AnimationFillMode::Forwards &&
    |                               ^^^^^^^^^^^^^^^^^ use of undeclared type or module `AnimationFillMode`
error[E0433]: failed to resolve: use of undeclared type or module `AnimationFillMode`
   --> components/style/animation.rs:393:31
    |
393 |             self.fill_mode != AnimationFillMode::Both
    |                               ^^^^^^^^^^^^^^^^^ use of undeclared type or module `AnimationFillMode`
error[E0412]: cannot find type `AnimationFillMode` in this scope
   --> components/style/animation.rs:189:20
    |
189 |     pub fill_mode: AnimationFillMode,
    |                    ^^^^^^^^^^^^^^^^^ not found in this scope
warning: ignoring -C extra-filename flag due to -o flag
error: aborting due to 6 previous errors
Some errors have detailed explanations: E0412, E0433.
For more information about an error, try `rustc --explain E0412`.
error: could not compile `style`.

and some more tests pass now 🎉

  ▶ Unexpected subtest result in /css/css-variables/variable-animation-substitute-within-keyframe-fallback.html:
  └ PASS [expected FAIL] Verify color before animation
  ▶ Unexpected subtest result in /css/css-variables/variable-animation-substitute-within-keyframe-multiple.html:
  └ PASS [expected FAIL] Verify color before animation
  ▶ Unexpected subtest result in /css/css-variables/variable-animation-substitute-into-keyframe.html:
  └ PASS [expected FAIL] Verify color before animation
  ▶ Unexpected subtest result in /css/css-variables/variable-animation-substitute-within-keyframe.html:
  └ PASS [expected FAIL] Verify color before animation
  ▶ Unexpected subtest result in /css/cssom/getComputedStyle-animations-replaced-into-ib-split.html:
  └ PASS [expected FAIL] getComputedStyle() should return animation styles for nodes just inserted into the document, even if they're in an IB-split

[mrobinson]

@bors-servo r=jdm,emilio

[bors-servo]

📌 Commit cd12c38 has been approved by jdm,emilio

[bors-servo]

⌛ Testing commit cd12c38 with merge abde2a6...

[bors-servo]

💔 Test failed - status-taskcluster

[jdm]

https://github.com/servo/servo/blob/cd12c38a6d4d074c53f1e5f89aab406e13bb1a56/tests/wpt/mozilla/meta/css/animations/__dir__.ini is missing from the 2020 metadata directory: https://github.com/servo/servo/tree/cd12c38a6d4d074c53f1e5f89aab406e13bb1a56/tests/wpt/mozilla/meta-layout-2020/css/animations

[mrobinson]

Okay. I've updated the change to include the ini file and have also rebased the layout_2020 test results for this directory. The tests will fail because support for animations in layout 2020 hasn't landed yet.

[jdm]

@bors-servo r+

[bors-servo]

📌 Commit 183f15d has been approved by jdm

[bors-servo]

⌛ Testing commit 183f15d with merge 50bd5c3...

[bors-servo]

☀️ Test successful - status-taskcluster
Approved by: jdm
Pushing 50bd5c3 to master...