style: Make sure to set the initial value of the transition even if w…

…e don't start it.

Otherwise we may get to the end of it directly, which is far from what we want.

components/style/animation.rs

@@ -437,21 +437,23 @@ pub fn start_transitions_if_applicable(new_animations_sender: &Sender<Animation>
                                                                      old_style,
                                                                      Arc::make_mut(new_style));
         for property_animation in property_animations {
-            // Per [1], don't trigger a new transition if the end state for that transition is
-            // the same as that of a transition that's already running on the same node.
+            // Set the property to the initial value.
+            //
+            // NB: get_mut is guaranteed to succeed since we called make_mut()
+            // above.
+            property_animation.update(Arc::get_mut(new_style).unwrap(), 0.0);
+
+            // Per [1], don't trigger a new transition if the end state for that
+            // transition is the same as that of a transition that's already
+            // running on the same node.
             //
             // [1]: https://drafts.csswg.org/css-transitions/#starting
             if possibly_expired_animations.iter().any(|animation| {
-                    animation.has_the_same_end_value_as(&property_animation)
-                }) {
+                animation.has_the_same_end_value_as(&property_animation)
+            }) {
                 continue
             }
 
-            // Set the property to the initial value.
-            // NB: get_mut is guaranteed to succeed since we called make_mut()
-            // above.
-            property_animation.update(Arc::get_mut(new_style).unwrap(), 0.0);
-
             // Kick off the animation.
             let box_style = new_style.get_box();
             let now = timer.seconds();