Derive PartialEq on the style Font structure

We check the hash first.

components/gfx/font_context.rs

@@ -321,12 +321,7 @@ struct LayoutFontGroupCacheKey {
 
 impl PartialEq for LayoutFontGroupCacheKey {
     fn eq(&self, other: &LayoutFontGroupCacheKey) -> bool {
-        self.pointer.font_family == other.pointer.font_family &&
+        self.pointer == other.pointer && self.size == other.size
-            self.pointer.font_stretch == other.pointer.font_stretch &&
-            self.pointer.font_style == other.pointer.font_style &&
-            self.pointer.font_weight as u16 == other.pointer.font_weight as u16 &&
-            self.pointer.font_variant == other.pointer.font_variant &&
-            self.size == other.size
     }
 }
 

components/style/properties.mako.rs

@@ -6029,7 +6029,11 @@ pub mod style_structs {
     use super::longhands;
 
     % for style_struct in STYLE_STRUCTS:
+        % if style_struct.name == "Font":
+        #[derive(Clone, HeapSizeOf)]
+        % else:
         #[derive(PartialEq, Clone, HeapSizeOf)]
+        % endif
         pub struct ${style_struct.name} {
             % for longhand in style_struct.longhands:
                 pub ${longhand.ident}: longhands::${longhand.ident}::computed_value::T,
@@ -6038,6 +6042,18 @@ pub mod style_structs {
                 pub hash: u64,
             % endif
         }
+        % if style_struct.name == "Font":
+
+        impl PartialEq for ${style_struct.name} {
+            fn eq(&self, other: &${style_struct.name}) -> bool {
+                self.hash == other.hash
+                % for longhand in style_struct.longhands:
+                    && self.${longhand.ident} == other.${longhand.ident}
+                % endfor
+            }
+        }
+        % endif
+
     % endfor
 }