Auto merge of #17783 - BorisChiou:stylo/animation/restrictions, r=nox

stylo: Bug 1374233 - Clamp interpolated values for properties which need to be restricted

Some properties only accept non-negative values, or values greater than or equal to one. It is possible to produce an negative interpolated values while using negative timing functions, so we have to apply a restriction to these values to avoid getting invalid values.

For example, line-height must be non-negative, but the output progress of some timing functions (e,g. cubic-bezier(0.25, -2, 0.75, 1)) may be a negative value, so the interpolated result of line-height is also negative.

---
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix Bug 1374233.
- [X] These changes do not require tests because we have tests in Gecko side already.

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1 files changed, 2 insertions, 1 deletions

diff --git a/components/style/servo/media_queries.rs b/components/style/servo/media_queries.rs
index 6904051af18..9b47d231c97 100644
--- a/components/style/servo/media_queries.rs
+++ b/components/style/servo/media_queries.rs
@@ -60,7 +60,8 @@ impl Device {
             media_type: media_type,
             viewport_size: viewport_size,
             device_pixel_ratio: device_pixel_ratio,
-            root_font_size: AtomicIsize::new(font_size::get_initial_value().0 as isize), // FIXME(bz): Seems dubious?
+            // FIXME(bz): Seems dubious?
+            root_font_size: AtomicIsize::new(font_size::get_initial_value().value() as isize),
             used_root_font_size: AtomicBool::new(false),
         }
     }