PropertyAnimation: Make iteration-count: n run animations n times

Side-effect: The code handles invalid inputs to duration/delay better.

Author: hunger

docs/langref.md

@@ -678,7 +678,8 @@ Animation can be configured with the following parameter:
 
 * `delay`: the amount of time to wait before starting the animation
 * `duration`: the amount of time it takes for the animation to complete
-* `loop-count`: FIXME
+* `iteration-count`: The number of times a animation should run. A negative value specifies
+    infinite reruns. Fractual values are possible.
 * `easing`: can be `linear`, `ease`, `ease-in`, `ease-out`, `ease-in-out`, `cubic-bezier(a, b, c, d)` as in CSS
 
 It is also possible to animate several properties with the same animation:

internal/compiler/builtins.60

@@ -408,7 +408,7 @@ PropertyAnimation := _ {
     property <duration> delay;
     property <duration> duration;
     property <easing> easing;
-    property <int> loop-count;
+    property <float> iteration-count: 1.0;
     //-is_non_item_type
 }
 

internal/compiler/llr/lower_expression.rs

@@ -370,7 +370,7 @@ pub fn lower_animation(a: &PropertyAnimation, ctx: &ExpressionContext<'_>) -> An
     fn animation_fields() -> impl Iterator<Item = (String, Type)> {
         IntoIterator::into_iter([
             ("duration".to_string(), Type::Int32),
-            ("loop-count".to_string(), Type::Int32),
+            ("iteration-count".to_string(), Type::Float32),
             ("easing".to_string(), Type::Easing),
             ("delay".to_string(), Type::Int32),
         ])

internal/core/items.rs

@@ -988,7 +988,7 @@ pub struct PropertyAnimation {
     #[rtti_field]
     pub duration: i32,
     #[rtti_field]
-    pub loop_count: i32,
+    pub iteration_count: f32,
     #[rtti_field]
     pub easing: crate::animations::EasingCurve,
 }