LibWeb: Remove concept of CSS pseudo-properties

We don't need them any more, so they're gone. :^)

Meta/Lagom/Tools/CodeGenerators/LibWeb/Generate_CSS_PropertyID_cpp.cpp

@@ -169,37 +169,6 @@ bool is_inherited_property(PropertyID property_id)
     }
 }
 
-bool is_pseudo_property(PropertyID property_id)
-{
-    switch (property_id) {
-)~~~");
-
-    properties.for_each_member([&](auto& name, auto& value) {
-        VERIFY(value.is_object());
-
-        bool pseudo = false;
-        if (value.as_object().has("pseudo")) {
-            auto& pseudo_value = value.as_object().get("pseudo");
-            VERIFY(pseudo_value.is_bool());
-            pseudo = pseudo_value.as_bool();
-        }
-
-        if (pseudo) {
-            auto member_generator = generator.fork();
-            member_generator.set("name:titlecase", title_casify(name));
-            member_generator.append(R"~~~(
-    case PropertyID::@name:titlecase@:
-        return true;
-)~~~");
-        }
-    });
-
-    generator.append(R"~~~(
-    default:
-        return false;
-    }
-}
-
 RefPtr<StyleValue> property_initial_value(PropertyID property_id)
 {
     static HashMap<PropertyID, NonnullRefPtr<StyleValue>> initial_values;

Meta/Lagom/Tools/CodeGenerators/LibWeb/Generate_CSS_PropertyID_h.cpp

@@ -104,7 +104,6 @@ PropertyID property_id_from_camel_case_string(StringView);
 PropertyID property_id_from_string(const StringView&);
 const char* string_from_property_id(PropertyID);
 bool is_inherited_property(PropertyID);
-bool is_pseudo_property(PropertyID);
 RefPtr<StyleValue> property_initial_value(PropertyID);
 
 bool property_accepts_value(PropertyID, StyleValue&);

Userland/Libraries/LibWeb/CSS/StyleComputer.cpp

@@ -123,13 +123,8 @@ static bool contains(Edge a, Edge b)
     return a == b || b == Edge::All;
 }
 
-static void set_property_expanding_shorthands(StyleProperties& style, CSS::PropertyID property_id, StyleValue const& value, DOM::Document& document, bool is_internally_generated_pseudo_property = false)
+static void set_property_expanding_shorthands(StyleProperties& style, CSS::PropertyID property_id, StyleValue const& value, DOM::Document& document)
 {
-    if (is_pseudo_property(property_id) && !is_internally_generated_pseudo_property) {
-        dbgln("Ignoring non-internally-generated pseudo property: {}", string_from_property_id(property_id));
-        return;
-    }
-
     auto assign_edge_values = [&style](PropertyID top_property, PropertyID right_property, PropertyID bottom_property, PropertyID left_property, auto const& values) {
         if (values.size() == 4) {
             style.set_property(top_property, values[0]);