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

style: Add support to test animations programatically.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #12120

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- [x] There are tests for these changes OR

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

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1 files changed, 5 insertions, 0 deletions

diff --git a/components/script_layout_interface/message.rs b/components/script_layout_interface/message.rs
index 22370b043c3..ce97c805bb2 100644
--- a/components/script_layout_interface/message.rs
+++ b/components/script_layout_interface/message.rs
@@ -40,6 +40,11 @@ pub enum Msg {
     /// Requests that the layout thread render the next frame of all animations.
     TickAnimations,
 
+    /// Updates layout's timer for animation testing from script.
+    ///
+    /// The inner field is the number of *milliseconds* to advance.
+    AdvanceClockMs(i32),
+
     /// Requests that the layout thread reflow with a newly-loaded Web font.
     ReflowWithNewlyLoadedWebFont,