Get rid of some of our custom additional methods in favor of clonable keywords.

Now that I'm pretty convinced we can auto-generate these and make them fast, we can
ditch the additional complexity.

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

@@ -7,7 +7,7 @@
 <% from data import Method %>
 
 <% data.new_style_struct("Border", inherited=False, gecko_ffi_name="nsStyleBorder",
-                   additional_methods=[Method("border_" + side + "_is_none_or_hidden_and_has_nonzero_width",
+                   additional_methods=[Method("border_" + side + "_has_nonzero_width",
                                               "bool") for side in ["top", "right", "bottom", "left"]]) %>
 
 % for side in ["top", "right", "bottom", "left"]:
@@ -15,7 +15,7 @@
 % endfor
 
 % for side in ["top", "right", "bottom", "left"]:
-    ${helpers.predefined_type("border-%s-style" % side, "BorderStyle", "specified::BorderStyle::none")}
+    ${helpers.predefined_type("border-%s-style" % side, "BorderStyle", "specified::BorderStyle::none", need_clone=True)}
 % endfor
 
 % for side in ["top", "right", "bottom", "left"]:

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

@@ -9,10 +9,7 @@
 <% data.new_style_struct("Box",
                          inherited=False,
                          gecko_ffi_name="nsStyleDisplay",
-                         additional_methods=[Method("is_floated", "bool"),
+                         additional_methods=[Method("transition_count", "usize")]) %>
-                                             Method("overflow_x_is_visible", "bool"),
-                                             Method("overflow_y_is_visible", "bool"),
-                                             Method("transition_count", "usize")]) %>
 
 // TODO(SimonSapin): don't parse `inline-table`, since we don't support it
 <%helpers:longhand name="display" need_clone="True" custom_cascade="${product == 'servo'}">
@@ -89,7 +86,7 @@
 
 ${helpers.single_keyword("position", "static absolute relative fixed", need_clone=True, extra_gecko_values="sticky")}
 
-<%helpers:single_keyword_computed name="float" values="none left right" gecko_ffi_name="mFloats">
+<%helpers:single_keyword_computed name="float" values="none left right" need_clone="True" gecko_ffi_name="mFloats">
     impl ToComputedValue for SpecifiedValue {
         type ComputedValue = computed_value::T;
 

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

@@ -9,12 +9,12 @@
 <% data.new_style_struct("Outline",
                          inherited=False,
                          gecko_ffi_name="nsStyleOutline",
-                         additional_methods=[Method("outline_is_none_or_hidden_and_has_nonzero_width", "bool")]) %>
+                         additional_methods=[Method("outline_has_nonzero_width", "bool")]) %>
 
 // TODO(pcwalton): `invert`
 ${helpers.predefined_type("outline-color", "CSSColor", "::cssparser::Color::CurrentColor")}
 
-<%helpers:longhand name="outline-style">
+<%helpers:longhand name="outline-style" need_clone="True">
     pub use values::specified::BorderStyle as SpecifiedValue;
     pub fn get_initial_value() -> SpecifiedValue { SpecifiedValue::none }
     pub mod computed_value {

components/style/properties/properties.mako.rs

@@ -277,10 +277,11 @@ pub mod longhands {
                      internal=True)}
 
     // FIXME(pcwalton, #2742): Implement scrolling for `scroll` and `auto`.
-    ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", gecko_constant_prefix="NS_STYLE_OVERFLOW")}
+    ${helpers.single_keyword("overflow-x", "visible hidden scroll auto", need_clone=True,
+                             gecko_constant_prefix="NS_STYLE_OVERFLOW")}
 
     // FIXME(pcwalton, #2742): Implement scrolling for `scroll` and `auto`.
-    <%helpers:longhand name="overflow-y">
+    <%helpers:longhand name="overflow-y" need_clone="True">
         use super::overflow_x;
 
         use cssparser::ToCss;
@@ -5719,8 +5720,10 @@ pub mod style_structs {
             % endfor
             % if style_struct.trait_name == "Border":
                 % for side in ["top", "right", "bottom", "left"]:
-                fn border_${side}_is_none_or_hidden_and_has_nonzero_width(&self) -> bool {
+                fn clone_border_${side}_style(&self) -> longhands::border_${side}_style::computed_value::T {
-                    self.border_${side}_style.none_or_hidden() &&
+                    self.border_${side}_style.clone()
+                }
+                fn border_${side}_has_nonzero_width(&self) -> bool {
                     self.border_${side}_width != ::app_units::Au(0)
                 }
                 % endfor
@@ -5731,14 +5734,14 @@ pub mod style_structs {
                 fn clone_position(&self) -> longhands::position::computed_value::T {
                     self.position.clone()
                 }
-                fn is_floated(&self) -> bool {
+                fn clone_float(&self) -> longhands::float::computed_value::T {
-                    self.float != longhands::float::SpecifiedValue::none
+                    self.float.clone()
                 }
-                fn overflow_x_is_visible(&self) -> bool {
+                fn clone_overflow_x(&self) -> longhands::overflow_x::computed_value::T {
-                    self.overflow_x == longhands::overflow_x::computed_value::T::visible
+                    self.overflow_x.clone()
                 }
-                fn overflow_y_is_visible(&self) -> bool {
+                fn clone_overflow_y(&self) -> longhands::overflow_y::computed_value::T {
-                    self.overflow_y.0 == longhands::overflow_x::computed_value::T::visible
+                    self.overflow_y.clone()
                 }
                 fn transition_count(&self) -> usize {
                     self.transition_property.0.len()
@@ -5778,8 +5781,11 @@ pub mod style_structs {
                     self._servo_text_decorations_in_effect.clone()
                 }
             % elif style_struct.trait_name == "Outline":
-                fn outline_is_none_or_hidden_and_has_nonzero_width(&self) -> bool {
+                fn clone_outline_style(&self) -> longhands::outline_style::computed_value::T {
-                    self.outline_style.none_or_hidden() && self.outline_width != ::app_units::Au(0)
+                    self.outline_style.clone()
+                }
+                fn outline_has_nonzero_width(&self) -> bool {
+                    self.outline_width != ::app_units::Au(0)
                 }
             % elif style_struct.trait_name == "Text":
                 fn has_underline(&self) -> bool {
@@ -6438,7 +6444,7 @@ pub fn cascade<C: ComputedValues>(
     let positioned = matches!(style.get_box().clone_position(),
         longhands::position::SpecifiedValue::absolute |
         longhands::position::SpecifiedValue::fixed);
-    let floated = style.get_box().is_floated();
+    let floated = style.get_box().clone_float() != longhands::float::SpecifiedValue::none;
     if positioned || floated || is_root_element {
         use computed_values::display::T;
 
@@ -6472,7 +6478,8 @@ pub fn cascade<C: ComputedValues>(
     {
         use computed_values::overflow_x::T as overflow;
         use computed_values::overflow_y;
-        match (style.get_box().overflow_x_is_visible(), style.get_box().overflow_y_is_visible()) {
+        match (style.get_box().clone_overflow_x() == longhands::overflow_x::computed_value::T::visible,
+               style.get_box().clone_overflow_y().0 == longhands::overflow_x::computed_value::T::visible) {
             (true, true) => {}
             (true, _) => {
                 style.mutate_box().set_overflow_x(overflow::auto);
@@ -6487,13 +6494,15 @@ pub fn cascade<C: ComputedValues>(
     // The initial value of border-*-width may be changed at computed value time.
     % for side in ["top", "right", "bottom", "left"]:
         // Like calling to_computed_value, which wouldn't type check.
-        if style.get_border().border_${side}_is_none_or_hidden_and_has_nonzero_width() {
+        if style.get_border().clone_border_${side}_style().none_or_hidden() &&
+           style.get_border().border_${side}_has_nonzero_width() {
             style.mutate_border().set_border_${side}_width(Au(0));
         }
     % endfor
 
     // The initial value of outline width may be changed at computed value time.
-    if style.get_outline().outline_is_none_or_hidden_and_has_nonzero_width() {
+    if style.get_outline().clone_outline_style().none_or_hidden() &&
+       style.get_outline().outline_has_nonzero_width() {
         style.mutate_outline().set_outline_width(Au(0));
     }
 

ports/geckolib/properties.mako.rs

@@ -276,7 +276,7 @@ ${caller.body()}
 // iteratively implement more and more methods.
 <%self:impl_trait style_struct_name="Border"
                   skip_longhands="${['border-left-color', 'border-left-style']}"
-                  skip_additionals="${['border_bottom_is_none_or_hidden_and_has_nonzero_width']}">
+                  skip_additionals="${['border_bottom_has_nonzero_width']}">
     fn set_border_left_color(&mut self, _: longhands::border_left_color::computed_value::T) {
         unimplemented!()
     }
@@ -289,7 +289,10 @@ ${caller.body()}
     fn copy_border_left_style_from(&mut self, _: &Self) {
         unimplemented!()
     }
-    fn border_bottom_is_none_or_hidden_and_has_nonzero_width(&self) -> bool {
+    fn clone_border_left_style(&self) -> longhands::border_left_style::computed_value::T {
+        unimplemented!()
+    }
+    fn border_bottom_has_nonzero_width(&self) -> bool {
         unimplemented!()
     }
 </%self:impl_trait>