Auto merge of #12392 - emilio:test-animations, r=SimonSapin

style: Add support to test animations programatically.

<!-- Please describe your changes on the following line: -->

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12120

<!-- Either: -->
- [x] There are tests for these changes OR

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

r? @SimonSapin for the style changes, @Ms2ger or @jdm for the dom and test changes

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/12392)
<!-- Reviewable:end -->

1 files changed, 5 insertions, 0 deletions

diff --git a/components/style/context.rs b/components/style/context.rs
index 3515728b4cf..f1c5ac3f307 100644
--- a/components/style/context.rs
+++ b/components/style/context.rs
@@ -15,6 +15,7 @@ use std::cell::RefCell;
 use std::collections::HashMap;
 use std::sync::mpsc::Sender;
 use std::sync::{Arc, Mutex, RwLock};
+use timer::Timer;
 
 /// This structure is used to create a local style context from a shared one.
 pub struct LocalStyleContextCreationInfo {
@@ -57,6 +58,10 @@ pub struct SharedStyleContext {
 
     /// Data needed to create the local style context from the shared one.
     pub local_context_creation_data: Mutex<LocalStyleContextCreationInfo>,
+
+    /// The current timer for transitions and animations. This is needed to test
+    /// them.
+    pub timer: Timer,
 }
 
 pub struct LocalStyleContext {