style: remove is_servo(), as_servo() and as_servo_mut()

This commit adds a need_index prop to the style system, and autogenerates
iterators, and a get_xxx_mod(i) function from a get_xxx_prop() and
get_xxx_at(index) functions.

This allows us to (finally!) take rid of the as_servo() hack. There are a few
unimplemented clones, but I'm just too lazy for that right now.

components/style/animation.rs

@@ -405,11 +405,6 @@ pub fn maybe_start_animations<Impl: SelectorImplExt>(context: &SharedStyleContex
 {
     let mut had_animations = false;
 
-    // FIXME(emilio): Implement animations for geckolib.
-    if !new_style.is_servo() {
-        return false;
-    }
-
     let box_style = new_style.get_box();
     for (i, name) in box_style.animation_name_iter().enumerate() {
         debug!("maybe_start_animations: name={}", name);

components/style/properties/data.py

@@ -57,7 +57,6 @@ def __init__(self, style_struct, name, animatable=None, derived_from=None, keywo
         self.experimental = ("layout.%s.enabled" % name) if experimental else None
         self.custom_cascade = custom_cascade
         self.internal = internal
-        self.need_clone = need_clone
         self.need_index = need_index
         self.gecko_ffi_name = gecko_ffi_name or "m" + self.camel_case
         self.derived_from = (derived_from or "").split()
@@ -72,6 +71,12 @@ def __init__(self, style_struct, name, animatable=None, derived_from=None, keywo
             assert animatable == "True" or animatable == "False"
             self.animatable = animatable == "True"
 
+        # NB: Animatable implies clone because a property animation requires a
+        # copy of the computed value.
+        #
+        # See components/style/helpers/animated_properties.mako.rs.
+        self.need_clone = need_clone or self.animatable
+
 
 class Shorthand(object):
     def __init__(self, name, sub_properties, experimental=False, internal=False):

components/style/properties/helpers/animated_properties.mako.rs

@@ -127,22 +127,17 @@ impl AnimatedProperty {
         }
     }
 
-    // NB: Transition properties need clone
     pub fn from_transition_property<C: ComputedValues>(transition_property: &TransitionProperty,
                                                        old_style: &C,
                                                        new_style: &C) -> AnimatedProperty {
-        // TODO: Generalise this for GeckoLib, adding clone_xxx to the
-        // appropiate longhands.
-        let old_style = old_style.as_servo();
-        let new_style = new_style.as_servo();
         match *transition_property {
             TransitionProperty::All => panic!("Can't use TransitionProperty::All here."),
             % for prop in data.longhands:
                 % if prop.animatable:
                     TransitionProperty::${prop.camel_case} => {
                         AnimatedProperty::${prop.camel_case}(
-                            old_style.get_${prop.style_struct.ident.strip("_")}().${prop.ident}.clone(),
-                            new_style.get_${prop.style_struct.ident.strip("_")}().${prop.ident}.clone())
+                            old_style.get_${prop.style_struct.ident.strip("_")}().clone_${prop.ident}(),
+                            new_style.get_${prop.style_struct.ident.strip("_")}().clone_${prop.ident}())
                     }
                 % endif
             % endfor

components/style/properties/properties.mako.rs

@@ -1246,14 +1246,6 @@ pub trait ComputedValues : Debug + Clone + Send + Sync + 'static {
         type Concrete${style_struct.trait_name}: style_struct_traits::${style_struct.trait_name};
     % endfor
 
-        // Temporary bailout case for stuff we haven't made work with the trait
-        // yet - panics for non-Servo implementations.
-        //
-        // Used only for animations. Don't use it in other places.
-        fn is_servo(&self) -> bool;
-        fn as_servo<'a>(&'a self) -> &'a ServoComputedValues;
-        fn as_servo_mut<'a>(&'a mut self) -> &'a mut ServoComputedValues;
-
         fn new(custom_properties: Option<Arc<::custom_properties::ComputedValuesMap>>,
                shareable: bool,
                writing_mode: WritingMode,
@@ -1302,13 +1294,6 @@ impl ComputedValues for ServoComputedValues {
         type Concrete${style_struct.trait_name} = style_structs::${style_struct.servo_struct_name};
     % endfor
 
-        #[inline]
-        fn is_servo(&self) -> bool { true }
-        #[inline]
-        fn as_servo<'a>(&'a self) -> &'a ServoComputedValues { self }
-        #[inline]
-        fn as_servo_mut<'a>(&'a mut self) -> &'a mut ServoComputedValues { self }
-
         fn new(custom_properties: Option<Arc<::custom_properties::ComputedValuesMap>>,
                shareable: bool,
                writing_mode: WritingMode,

components/style/values.rs

@@ -1194,6 +1194,11 @@ pub mod specified {
         pub fn radians(self) -> f32 {
             self.0
         }
+
+        #[inline]
+        pub fn from_radians(r: f32) -> Self {
+            Angle(r)
+        }
     }
 
     const RAD_PER_DEG: CSSFloat = PI / 180.0;