Auto merge of #14703 - canaltinova:perspective-transform, r=Wafflespeanut

Add gecko glue for perspective/transform properties

<!-- Please describe your changes on the following line: -->
To be able to add glue for these properties,  we needed to change their structs. They are moved from effects to box and added stylo glue.
This PR covers these properties:
- perspective
- perspective-origin
- backface-visibility
- transform-box
- transform-style
- transform-origin

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

<!-- Either: -->
- [X] These changes do not require tests because they are stylo changes

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14703)
<!-- Reviewable:end -->

components/layout/display_list_builder.rs

@@ -1567,9 +1567,9 @@ impl FragmentDisplayListBuilding for Fragment {
         let overflow = base_flow.overflow.paint.translate(&-border_box_offset);
 
         let transform = self.transform_matrix(&border_box);
-        let perspective = match self.style().get_effects().perspective {
+        let perspective = match self.style().get_box().perspective {
             Either::First(length) => {
-                let perspective_origin = self.style().get_effects().perspective_origin;
+                let perspective_origin = self.style().get_box().perspective_origin;
                 let perspective_origin =
                     Point2D::new(model::specified(perspective_origin.horizontal,
                                                   border_box.size.width).to_f32_px(),
@@ -1822,7 +1822,7 @@ impl FragmentDisplayListBuilding for Fragment {
             Some(ref operations) => operations,
         };
 
-        let transform_origin = &self.style.get_effects().transform_origin;
+        let transform_origin = &self.style.get_box().transform_origin;
         let transform_origin_x = model::specified(transform_origin.horizontal,
                                                   stacking_relative_border_box.size
                                                                               .width).to_f32_px();

components/layout/fragment.rs

@@ -2370,7 +2370,7 @@ impl Fragment {
 
         // TODO(mrobinson): Determine if this is necessary, since blocks with
         // transformations already create stacking contexts.
-        if let Either::First(ref _length) = self.style().get_effects().perspective {
+        if let Either::First(ref _length) = self.style().get_box().perspective {
             return true
         }
 

components/style/gecko/values.rs

@@ -9,7 +9,7 @@ use cssparser::RGBA;
 use gecko_bindings::structs::{nsStyleCoord, StyleShapeRadius};
 use gecko_bindings::sugar::ns_style_coord::{CoordData, CoordDataMut, CoordDataValue};
 use std::cmp::max;
-use values::{Auto, Either};
+use values::{Auto, Either, None_};
 use values::computed::{Angle, LengthOrPercentageOrNone, Number};
 use values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto};
 use values::computed::basic_shape::ShapeRadius;
@@ -207,6 +207,20 @@ impl GeckoStyleCoordConvertible for Auto {
     }
 }
 
+impl GeckoStyleCoordConvertible for None_ {
+    fn to_gecko_style_coord<T: CoordDataMut>(&self, coord: &mut T) {
+        coord.set_value(CoordDataValue::None)
+    }
+
+    fn from_gecko_style_coord<T: CoordData>(coord: &T) -> Option<Self> {
+        if let CoordDataValue::None = coord.as_value() {
+            Some(None_)
+        } else {
+            None
+        }
+    }
+}
+
 pub fn convert_rgba_to_nscolor(rgba: &RGBA) -> u32 {
     (((rgba.alpha * 255.0).round() as u32) << 24) |
     (((rgba.blue  * 255.0).round() as u32) << 16) |

components/style/properties/gecko.mako.rs

@@ -475,8 +475,6 @@ impl Debug for ${style_struct.gecko_struct_name} {
     # Make a list of types we can't auto-generate.
     #
     force_stub = [];
-    # These are currently being shuffled to a different style struct on the gecko side.
-    force_stub += ["backface-visibility", "transform-box", "transform-style"]
     # These live in an nsFont member in Gecko. Should be straightforward to do manually.
     force_stub += ["font-variant"]
     # These have unusual representations in gecko.
@@ -505,6 +503,7 @@ impl Debug for ${style_struct.gecko_struct_name} {
         "LengthOrPercentage": impl_style_coord,
         "LengthOrPercentageOrAuto": impl_style_coord,
         "LengthOrPercentageOrNone": impl_style_coord,
+        "LengthOrNone": impl_style_coord,
         "Number": impl_simple,
         "Opacity": impl_simple,
         "CSSColor": impl_color,
@@ -1053,7 +1052,7 @@ fn static_assert() {
 <% skip_box_longhands= """display overflow-y vertical-align
                           -moz-binding page-break-before page-break-after
                           scroll-snap-points-x scroll-snap-points-y transform
-                          scroll-snap-type-y""" %>
+                          scroll-snap-type-y perspective-origin transform-origin""" %>
 <%self:impl_trait style_struct_name="Box" skip_longhands="${skip_box_longhands}">
 
     // We manually-implement the |display| property until we get general
@@ -1325,6 +1324,40 @@ fn static_assert() {
 
     ${impl_keyword('scroll_snap_type_y', 'mScrollSnapTypeY', scroll_snap_type_keyword, need_clone=False)}
 
+    pub fn set_perspective_origin(&mut self, v: longhands::perspective_origin::computed_value::T) {
+        self.gecko.mPerspectiveOrigin[0].set(v.horizontal);
+        self.gecko.mPerspectiveOrigin[1].set(v.vertical);
+    }
+
+    pub fn copy_perspective_origin_from(&mut self, other: &Self) {
+        self.gecko.mPerspectiveOrigin[0].copy_from(&other.gecko.mPerspectiveOrigin[0]);
+        self.gecko.mPerspectiveOrigin[1].copy_from(&other.gecko.mPerspectiveOrigin[1]);
+    }
+
+    pub fn set_transform_origin(&mut self, v: longhands::transform_origin::computed_value::T) {
+        self.gecko.mTransformOrigin[0].set(v.horizontal);
+        self.gecko.mTransformOrigin[1].set(v.vertical);
+        self.gecko.mTransformOrigin[2].set(v.depth);
+    }
+
+    pub fn copy_transform_origin_from(&mut self, other: &Self) {
+        self.gecko.mTransformOrigin[0].copy_from(&other.gecko.mTransformOrigin[0]);
+        self.gecko.mTransformOrigin[1].copy_from(&other.gecko.mTransformOrigin[1]);
+        self.gecko.mTransformOrigin[2].copy_from(&other.gecko.mTransformOrigin[2]);
+    }
+
+    pub fn clone_transform_origin(&self) -> longhands::transform_origin::computed_value::T {
+        use properties::longhands::transform_origin::computed_value::T;
+        use values::computed::LengthOrPercentage;
+        T {
+            horizontal: LengthOrPercentage::from_gecko_style_coord(&self.gecko.mTransformOrigin[0])
+                .expect("clone for LengthOrPercentage failed"),
+            vertical: LengthOrPercentage::from_gecko_style_coord(&self.gecko.mTransformOrigin[1])
+                .expect("clone for LengthOrPercentage failed"),
+            depth: Au::from_gecko_style_coord(&self.gecko.mTransformOrigin[2])
+                .expect("clone for Length failed"),
+        }
+    }
 </%self:impl_trait>
 
 <%def name="simple_image_array_property(name, shorthand, field_name)">

components/style/properties/longhand/box.mako.rs

@@ -1526,6 +1526,228 @@ ${helpers.single_keyword("resize",
                          products="gecko",
                          animatable=False)}
 
+
+// https://drafts.csswg.org/css-transforms/#perspective
+${helpers.predefined_type("perspective",
+                          "LengthOrNone",
+                          "Either::Second(None_)",
+                          gecko_ffi_name="mChildPerspective",
+                          animatable=True)}
+
+// FIXME: This prop should be animatable
+// https://drafts.csswg.org/css-transforms/#perspective-origin-property
+<%helpers:longhand name="perspective-origin" animatable="False">
+    use std::fmt;
+    use style_traits::ToCss;
+    use values::HasViewportPercentage;
+    use values::specified::{LengthOrPercentage, Percentage};
+
+    pub mod computed_value {
+        use values::computed::LengthOrPercentage;
+
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        pub struct T {
+            pub horizontal: LengthOrPercentage,
+            pub vertical: LengthOrPercentage,
+        }
+    }
+
+    impl ToCss for computed_value::T {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            try!(self.horizontal.to_css(dest));
+            try!(dest.write_str(" "));
+            self.vertical.to_css(dest)
+        }
+    }
+
+    impl HasViewportPercentage for SpecifiedValue {
+        fn has_viewport_percentage(&self) -> bool {
+            self.horizontal.has_viewport_percentage() || self.vertical.has_viewport_percentage()
+        }
+    }
+
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    pub struct SpecifiedValue {
+        horizontal: LengthOrPercentage,
+        vertical: LengthOrPercentage,
+    }
+
+    impl ToCss for SpecifiedValue {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            try!(self.horizontal.to_css(dest));
+            try!(dest.write_str(" "));
+            self.vertical.to_css(dest)
+        }
+    }
+
+    #[inline]
+    pub fn get_initial_value() -> computed_value::T {
+        computed_value::T {
+            horizontal: computed::LengthOrPercentage::Percentage(0.5),
+            vertical: computed::LengthOrPercentage::Percentage(0.5),
+        }
+    }
+
+    pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue,()> {
+        let result = try!(super::parse_origin(context, input));
+        match result.depth {
+            Some(_) => Err(()),
+            None => Ok(SpecifiedValue {
+                horizontal: result.horizontal.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
+                vertical: result.vertical.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
+            })
+        }
+    }
+
+    impl ToComputedValue for SpecifiedValue {
+        type ComputedValue = computed_value::T;
+
+        #[inline]
+        fn to_computed_value(&self, context: &Context) -> computed_value::T {
+            computed_value::T {
+                horizontal: self.horizontal.to_computed_value(context),
+                vertical: self.vertical.to_computed_value(context),
+            }
+        }
+
+        #[inline]
+        fn from_computed_value(computed: &computed_value::T) -> Self {
+            SpecifiedValue {
+                horizontal: ToComputedValue::from_computed_value(&computed.horizontal),
+                vertical: ToComputedValue::from_computed_value(&computed.vertical),
+            }
+        }
+    }
+</%helpers:longhand>
+
+// https://drafts.csswg.org/css-transforms/#backface-visibility-property
+${helpers.single_keyword("backface-visibility",
+                         "visible hidden",
+                         animatable=False)}
+
+// https://drafts.csswg.org/css-transforms/#transform-box
+${helpers.single_keyword("transform-box",
+                         "border-box fill-box view-box",
+                         products="gecko",
+                         animatable=False)}
+
+// `auto` keyword is not supported in gecko yet.
+// https://drafts.csswg.org/css-transforms/#transform-style-property
+${helpers.single_keyword("transform-style",
+                         "auto flat preserve-3d" if product == "servo" else
+                         "flat preserve-3d",
+                         animatable=False)}
+
+// https://drafts.csswg.org/css-transforms/#transform-origin-property
+<%helpers:longhand name="transform-origin" animatable="True">
+    use app_units::Au;
+    use std::fmt;
+    use style_traits::ToCss;
+    use values::HasViewportPercentage;
+    use values::specified::{Length, LengthOrPercentage, Percentage};
+
+    pub mod computed_value {
+        use properties::animated_properties::Interpolate;
+        use values::computed::{Length, LengthOrPercentage};
+
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+        pub struct T {
+            pub horizontal: LengthOrPercentage,
+            pub vertical: LengthOrPercentage,
+            pub depth: Length,
+        }
+
+        impl Interpolate for T {
+            fn interpolate(&self, other: &Self, time: f64) -> Result<Self, ()> {
+                Ok(T {
+                    horizontal: try!(self.horizontal.interpolate(&other.horizontal, time)),
+                    vertical: try!(self.vertical.interpolate(&other.vertical, time)),
+                    depth: try!(self.depth.interpolate(&other.depth, time)),
+                })
+            }
+        }
+    }
+
+    impl HasViewportPercentage for SpecifiedValue {
+        fn has_viewport_percentage(&self) -> bool {
+            self.horizontal.has_viewport_percentage() ||
+            self.vertical.has_viewport_percentage() ||
+            self.depth.has_viewport_percentage()
+        }
+    }
+
+    #[derive(Clone, Copy, Debug, PartialEq)]
+    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+    pub struct SpecifiedValue {
+        horizontal: LengthOrPercentage,
+        vertical: LengthOrPercentage,
+        depth: Length,
+    }
+
+    impl ToCss for computed_value::T {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            try!(self.horizontal.to_css(dest));
+            try!(dest.write_str(" "));
+            try!(self.vertical.to_css(dest));
+            try!(dest.write_str(" "));
+            self.depth.to_css(dest)
+        }
+    }
+
+    impl ToCss for SpecifiedValue {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            try!(self.horizontal.to_css(dest));
+            try!(dest.write_str(" "));
+            try!(self.vertical.to_css(dest));
+            try!(dest.write_str(" "));
+            self.depth.to_css(dest)
+        }
+    }
+
+    #[inline]
+    pub fn get_initial_value() -> computed_value::T {
+        computed_value::T {
+            horizontal: computed::LengthOrPercentage::Percentage(0.5),
+            vertical: computed::LengthOrPercentage::Percentage(0.5),
+            depth: Au(0),
+        }
+    }
+
+    pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue,()> {
+        let result = try!(super::parse_origin(context, input));
+        Ok(SpecifiedValue {
+            horizontal: result.horizontal.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
+            vertical: result.vertical.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
+            depth: result.depth.unwrap_or(Length::Absolute(Au(0))),
+        })
+    }
+
+    impl ToComputedValue for SpecifiedValue {
+        type ComputedValue = computed_value::T;
+
+        #[inline]
+        fn to_computed_value(&self, context: &Context) -> computed_value::T {
+            computed_value::T {
+                horizontal: self.horizontal.to_computed_value(context),
+                vertical: self.vertical.to_computed_value(context),
+                depth: self.depth.to_computed_value(context),
+            }
+        }
+
+        #[inline]
+        fn from_computed_value(computed: &computed_value::T) -> Self {
+            SpecifiedValue {
+                horizontal: ToComputedValue::from_computed_value(&computed.horizontal),
+                vertical: ToComputedValue::from_computed_value(&computed.vertical),
+                depth: ToComputedValue::from_computed_value(&computed.depth),
+            }
+        }
+    }
+</%helpers:longhand>
+
 // Non-standard
 ${helpers.single_keyword("-moz-appearance",
                          """none button button-arrow-down button-arrow-next button-arrow-previous button-arrow-up

components/style/properties/longhand/effects.mako.rs

@@ -690,219 +690,6 @@ pub fn parse_origin(context: &ParserContext, input: &mut Parser) -> Result<Origi
     }
 }
 
-${helpers.single_keyword("backface-visibility",
-                         "visible hidden",
-                         animatable=False)}
-
-${helpers.single_keyword("transform-box",
-                         "border-box fill-box view-box",
-                         products="gecko",
-                         animatable=False)}
-
-${helpers.single_keyword("transform-style",
-                         "auto flat preserve-3d",
-                         animatable=False)}
-
-<%helpers:longhand name="transform-origin" products="servo" animatable="True">
-    use app_units::Au;
-    use std::fmt;
-    use style_traits::ToCss;
-    use values::HasViewportPercentage;
-    use values::specified::{Length, LengthOrPercentage, Percentage};
-
-    pub mod computed_value {
-        use properties::animated_properties::Interpolate;
-        use values::computed::{Length, LengthOrPercentage};
-
-        #[derive(Clone, Copy, Debug, PartialEq)]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-        pub struct T {
-            pub horizontal: LengthOrPercentage,
-            pub vertical: LengthOrPercentage,
-            pub depth: Length,
-        }
-
-        impl Interpolate for T {
-            fn interpolate(&self, other: &Self, time: f64) -> Result<Self, ()> {
-                Ok(T {
-                    horizontal: try!(self.horizontal.interpolate(&other.horizontal, time)),
-                    vertical: try!(self.vertical.interpolate(&other.vertical, time)),
-                    depth: try!(self.depth.interpolate(&other.depth, time)),
-                })
-            }
-        }
-    }
-
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            self.horizontal.has_viewport_percentage() ||
-            self.vertical.has_viewport_percentage() ||
-            self.depth.has_viewport_percentage()
-        }
-    }
-
-    #[derive(Clone, Copy, Debug, PartialEq)]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-    pub struct SpecifiedValue {
-        horizontal: LengthOrPercentage,
-        vertical: LengthOrPercentage,
-        depth: Length,
-    }
-
-    impl ToCss for computed_value::T {
-        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-            try!(self.horizontal.to_css(dest));
-            try!(dest.write_str(" "));
-            try!(self.vertical.to_css(dest));
-            try!(dest.write_str(" "));
-            self.depth.to_css(dest)
-        }
-    }
-
-    impl ToCss for SpecifiedValue {
-        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-            try!(self.horizontal.to_css(dest));
-            try!(dest.write_str(" "));
-            try!(self.vertical.to_css(dest));
-            try!(dest.write_str(" "));
-            self.depth.to_css(dest)
-        }
-    }
-
-    #[inline]
-    pub fn get_initial_value() -> computed_value::T {
-        computed_value::T {
-            horizontal: computed::LengthOrPercentage::Percentage(0.5),
-            vertical: computed::LengthOrPercentage::Percentage(0.5),
-            depth: Au(0),
-        }
-    }
-
-    pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue,()> {
-        let result = try!(super::parse_origin(context, input));
-        Ok(SpecifiedValue {
-            horizontal: result.horizontal.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
-            vertical: result.vertical.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
-            depth: result.depth.unwrap_or(Length::Absolute(Au(0))),
-        })
-    }
-
-    impl ToComputedValue for SpecifiedValue {
-        type ComputedValue = computed_value::T;
-
-        #[inline]
-        fn to_computed_value(&self, context: &Context) -> computed_value::T {
-            computed_value::T {
-                horizontal: self.horizontal.to_computed_value(context),
-                vertical: self.vertical.to_computed_value(context),
-                depth: self.depth.to_computed_value(context),
-            }
-        }
-
-        #[inline]
-        fn from_computed_value(computed: &computed_value::T) -> Self {
-            SpecifiedValue {
-                horizontal: ToComputedValue::from_computed_value(&computed.horizontal),
-                vertical: ToComputedValue::from_computed_value(&computed.vertical),
-                depth: ToComputedValue::from_computed_value(&computed.depth),
-            }
-        }
-    }
-</%helpers:longhand>
-
-${helpers.predefined_type("perspective",
-                          "LengthOrNone",
-                          "Either::Second(None_)",
-                          products="servo",
-                          animatable=True)}
-
-// FIXME: This prop should be animatable
-<%helpers:longhand name="perspective-origin" products="servo" animatable="False">
-    use std::fmt;
-    use style_traits::ToCss;
-    use values::HasViewportPercentage;
-    use values::specified::{LengthOrPercentage, Percentage};
-
-    pub mod computed_value {
-        use values::computed::LengthOrPercentage;
-
-        #[derive(Clone, Copy, Debug, PartialEq)]
-        #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-        pub struct T {
-            pub horizontal: LengthOrPercentage,
-            pub vertical: LengthOrPercentage,
-        }
-    }
-
-    impl ToCss for computed_value::T {
-        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-            try!(self.horizontal.to_css(dest));
-            try!(dest.write_str(" "));
-            self.vertical.to_css(dest)
-        }
-    }
-
-    impl HasViewportPercentage for SpecifiedValue {
-        fn has_viewport_percentage(&self) -> bool {
-            self.horizontal.has_viewport_percentage() || self.vertical.has_viewport_percentage()
-        }
-    }
-
-    #[derive(Clone, Copy, Debug, PartialEq)]
-    #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
-    pub struct SpecifiedValue {
-        horizontal: LengthOrPercentage,
-        vertical: LengthOrPercentage,
-    }
-
-    impl ToCss for SpecifiedValue {
-        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-            try!(self.horizontal.to_css(dest));
-            try!(dest.write_str(" "));
-            self.vertical.to_css(dest)
-        }
-    }
-
-    #[inline]
-    pub fn get_initial_value() -> computed_value::T {
-        computed_value::T {
-            horizontal: computed::LengthOrPercentage::Percentage(0.5),
-            vertical: computed::LengthOrPercentage::Percentage(0.5),
-        }
-    }
-
-    pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue,()> {
-        let result = try!(super::parse_origin(context, input));
-        match result.depth {
-            Some(_) => Err(()),
-            None => Ok(SpecifiedValue {
-                horizontal: result.horizontal.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
-                vertical: result.vertical.unwrap_or(LengthOrPercentage::Percentage(Percentage(0.5))),
-            })
-        }
-    }
-
-    impl ToComputedValue for SpecifiedValue {
-        type ComputedValue = computed_value::T;
-
-        #[inline]
-        fn to_computed_value(&self, context: &Context) -> computed_value::T {
-            computed_value::T {
-                horizontal: self.horizontal.to_computed_value(context),
-                vertical: self.vertical.to_computed_value(context),
-            }
-        }
-
-        #[inline]
-        fn from_computed_value(computed: &computed_value::T) -> Self {
-            SpecifiedValue {
-                horizontal: ToComputedValue::from_computed_value(&computed.horizontal),
-                vertical: ToComputedValue::from_computed_value(&computed.vertical),
-            }
-        }
-    }
-</%helpers:longhand>
-
 ${helpers.single_keyword("mix-blend-mode",
                          """normal multiply screen overlay darken lighten color-dodge
                             color-burn hard-light soft-light difference exclusion hue

components/style/properties/properties.mako.rs

@@ -1343,17 +1343,17 @@ impl ComputedValues {
             return transform_style::T::flat;
         }
 
-        if effects.transform_style == transform_style::T::auto {
+        if box_.transform_style == transform_style::T::auto {
             if box_.transform.0.is_some() {
                 return transform_style::T::flat;
             }
-            if let Either::First(ref _length) = effects.perspective {
+            if let Either::First(ref _length) = box_.perspective {
                 return transform_style::T::flat;
             }
         }
 
         // Return the computed value if not overridden by the above exceptions
-        effects.transform_style
+        box_.transform_style
     }
 
     pub fn transform_requires_layer(&self) -> bool {

components/style/servo/restyle_damage.rs

@@ -227,8 +227,8 @@ fn compute_damage(old: &ServoComputedValues, new: &ServoComputedValues) -> Servo
         get_position.top, get_position.left,
         get_position.right, get_position.bottom,
         get_effects.opacity,
-        get_box.transform, get_effects.transform_style, get_effects.transform_origin,
+        get_box.transform, get_box.transform_style, get_box.transform_origin,
-        get_effects.perspective, get_effects.perspective_origin
+        get_box.perspective, get_box.perspective_origin
     ]) || add_if_not_equal!(old, new, damage,
                             [REPAINT], [
         get_color.color, get_background.background_color,