Auto merge of #26407 - mrobinson:animation-restyle-model, r=jdm

Have animations more closely match the HTML spec

These two commits do two major things:

**Have animations ticks trigger a restyle**: This corrects synchronization issues with animations,
where the values used in layout are out of sync with what is returned by `getComputedStyle`.

**Tick the animation timer in script according to spec**: This greatly reduces the flakiness of
animation and transitions tests.

Fixes #13865.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #13865

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- [x] There are tests for these changes OR
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components/net_traits/image_cache.rs

@@ -14,15 +14,6 @@ use std::sync::Arc;
 // Aux structs and enums.
 // ======================================================================
 
-/// Whether a consumer is in a position to request images or not. This can occur
-/// when animations are being processed by the layout thread while the script
-/// thread is executing in parallel.
-#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
-pub enum CanRequestImages {
-    No,
-    Yes,
-}
-
 /// Indicating either entire image or just metadata availability
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub enum ImageOrMetadataAvailable {
@@ -119,7 +110,6 @@ pub trait ImageCache: Sync + Send {
         origin: ImmutableOrigin,
         cors_setting: Option<CorsSettings>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult;
 
     /// Add a listener for the provided pending image id, eventually called by
@@ -135,7 +125,6 @@ pub trait ImageCache: Sync + Send {
         cors_setting: Option<CorsSettings>,
         sender: IpcSender<PendingImageResponse>,
         use_placeholder: UsePlaceholder,
-        can_request: CanRequestImages,
     ) -> ImageCacheResult;
 
     /// Add a new listener for the given pending image id. If the image is already present,