LibWeb: Store font-width in ComputedProperties in computed form

Author: https://github.com/Calme1709
Commit: 335c8c7ffb
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6072
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/CSS/ComputedProperties.cpp

@@ -2109,4 +2109,9 @@ double ComputedProperties::font_weight() const
     return property(PropertyID::FontWeight).as_number().number();
 }
 
+Percentage ComputedProperties::font_width() const
+{
+    return property(PropertyID::FontWidth).as_percentage().percentage();
+}
+
 }