fonts: Add support for more @font-face features (#32164)

There are a couple major changes here:

1. Support is added for the `weight`, `style`, `stretch` and
   `unicode-range` declarations in `@font-face`.
2. Font matching in the font cache can return templates and
   `FontGroupFamily` can own mulitple templates. This is due to needing
   support for "composite fonts". These are `@font-face` declarations
   that only differ in their `unicode-range` definition.

This fixes a lot of non-determinism in font selection especially when
dealing with pages that define "composite faces." A notable example of
such a page is servo.org, which now consistently displays the correct
web font.

One test starts to fail due to an uncovered bug, but this will be fixed
in a followup change.

Fixes #20686.
Fixes #20684.

Co-authored-by: Mukilan Thiyagarajan <mukilan@igalia.com>

components/gfx/platform/freetype/android/font_list.rs

@@ -485,11 +485,7 @@ where
             },
             None => StyleFontStyle::NORMAL,
         };
-        let descriptor = FontTemplateDescriptor {
-            weight,
-            stretch,
-            style,
-        };
+        let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
         callback(FontTemplate::new_local(local_font_identifier, descriptor));
     };
 

components/gfx/platform/freetype/font.rs

@@ -173,11 +173,7 @@ impl PlatformFontMethods for PlatformFont {
             })
             .unwrap_or(FontStretch::NORMAL);
 
-        FontTemplateDescriptor {
-            weight,
-            stretch,
-            style,
-        }
+        FontTemplateDescriptor::new(weight, stretch, style)
     }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {

components/gfx/platform/freetype/font_list.rs

@@ -148,11 +148,7 @@ where
                 path: Atom::from(c_str_to_string(path as *const c_char)),
                 variation_index: index as i32,
             };
-            let descriptor = FontTemplateDescriptor {
-                weight,
-                stretch,
-                style,
-            };
+            let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
 
             callback(FontTemplate::new_local(local_font_identifier, descriptor))
         }

components/gfx/platform/macos/font.rs

@@ -190,11 +190,7 @@ impl PlatformFontMethods for PlatformFont {
 
     fn descriptor(&self) -> FontTemplateDescriptor {
         let traits = self.ctfont.all_traits();
-        FontTemplateDescriptor {
-            weight: traits.weight(),
-            stretch: traits.stretch(),
-            style: traits.style(),
-        }
+        FontTemplateDescriptor::new(traits.weight(), traits.stretch(), traits.style())
     }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {

components/gfx/platform/macos/font_list.rs

@@ -74,11 +74,8 @@ where
                 };
 
                 let traits = family_descriptor.traits();
-                let descriptor = FontTemplateDescriptor {
-                    weight: traits.weight(),
-                    stretch: traits.stretch(),
-                    style: traits.style(),
-                };
+                let descriptor =
+                    FontTemplateDescriptor::new(traits.weight(), traits.stretch(), traits.style());
                 let identifier = LocalFontIdentifier {
                     postscript_name: Atom::from(family_descriptor.font_name()),
                     path: Atom::from(path),

components/gfx/platform/windows/font.rs

@@ -186,11 +186,7 @@ impl PlatformFontMethods for PlatformFont {
             StyleFontStyle::NORMAL
         };
 
-        FontTemplateDescriptor {
-            weight,
-            stretch,
-            style,
-        }
+        FontTemplateDescriptor::new(weight, stretch, style)
     }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {