LibWeb: Remove now-unused null values from Selector enums

Now that we use a Variant for the SimpleSelector's data, we don't need
to instantiate empty structs or variables for the types that aren't
used, and so we can remove `PseudoElement::None`,
`PsuedoClass::Type::None` and `Attribute::MatchType::None`.

Also, we now always initialize a SimpleSelector with a type, so
`SimpleSelector::Type::Invalid` can go too.

Userland/Libraries/LibWeb/CSS/Selector.cpp

@@ -105,8 +105,6 @@ u32 Selector::specificity() const
             case SimpleSelector::Type::Universal:
                 // ignore the universal selector
                 break;
-            case SimpleSelector::Type::Invalid:
-                break;
             }
         }
     }

Userland/Libraries/LibWeb/CSS/Selector.h

@@ -21,7 +21,6 @@ using SelectorList = NonnullRefPtrVector<class Selector>;
 class Selector : public RefCounted<Selector> {
 public:
     enum class PseudoElement {
-        None,
         Before,
         After,
         FirstLine,
@@ -32,7 +31,6 @@ public:
 
     struct SimpleSelector {
         enum class Type {
-            Invalid,
             Universal,
             TagName,
             Id,
@@ -54,7 +52,6 @@ public:
 
         struct PseudoClass {
             enum class Type {
-                None,
                 Link,
                 Visited,
                 Hover,
@@ -81,7 +78,7 @@ public:
                 Active,
                 Lang,
             };
-            Type type { Type::None };
+            Type type;
 
             // FIXME: We don't need this field on every single SimpleSelector, but it's also annoying to malloc it somewhere.
             // Only used when "pseudo_class" is "NthChild" or "NthLastChild".
@@ -95,7 +92,6 @@ public:
 
         struct Attribute {
             enum class MatchType {
-                None,
                 HasAttribute,
                 ExactValueMatch,
                 ContainsWord,      // [att~=val]
@@ -104,12 +100,12 @@ public:
                 StartsWithString,  // [att^=val]
                 EndsWithString,    // [att$=val]
             };
-            MatchType match_type { MatchType::None };
+            MatchType match_type;
             FlyString name {};
             String value {};
         };
 
-        Type type { Type::Invalid };
+        Type type;
         Variant<Empty, Attribute, PseudoClass, PseudoElement, FlyString> value {};
 
         Attribute const& attribute() const { return value.get<Attribute>(); }
@@ -173,8 +169,6 @@ constexpr StringView pseudo_element_name(Selector::PseudoElement pseudo_element)
         return "first-letter"sv;
     case Selector::PseudoElement::Marker:
         return "marker"sv;
-    case Selector::PseudoElement::None:
-        break;
     }
     VERIFY_NOT_REACHED();
 }
@@ -234,8 +228,6 @@ constexpr StringView pseudo_class_name(Selector::SimpleSelector::PseudoClass::Ty
         return "where"sv;
     case Selector::SimpleSelector::PseudoClass::Type::Lang:
         return "lang"sv;
-    case Selector::SimpleSelector::PseudoClass::Type::None:
-        break;
     }
     VERIFY_NOT_REACHED();
 }

Userland/Libraries/LibWeb/CSS/SelectorEngine.cpp

@@ -95,9 +95,6 @@ static inline bool matches_attribute(CSS::Selector::SimpleSelector::Attribute co
         return element.attribute(attribute.name).starts_with(attribute.value);
     case CSS::Selector::SimpleSelector::Attribute::MatchType::EndsWithString:
         return element.attribute(attribute.name).ends_with(attribute.value);
-    case CSS::Selector::SimpleSelector::Attribute::MatchType::None:
-        VERIFY_NOT_REACHED();
-        break;
     }
 
     return false;
@@ -124,8 +121,6 @@ static inline DOM::Element const* next_sibling_with_same_tag_name(DOM::Element c
 static inline bool matches_pseudo_class(CSS::Selector::SimpleSelector::PseudoClass const& pseudo_class, DOM::Element const& element)
 {
     switch (pseudo_class.type) {
-    case CSS::Selector::SimpleSelector::PseudoClass::Type::None:
-        break;
     case CSS::Selector::SimpleSelector::PseudoClass::Type::Link:
         return element.is_link();
     case CSS::Selector::SimpleSelector::PseudoClass::Type::Visited:

Userland/Libraries/LibWeb/Dump.cpp

@@ -333,9 +333,6 @@ void dump_selector(StringBuilder& builder, CSS::Selector const& selector)
             auto& simple_selector = relative_selector.simple_selectors[i];
             char const* type_description = "Unknown";
             switch (simple_selector.type) {
-            case CSS::Selector::SimpleSelector::Type::Invalid:
-                type_description = "Invalid";
-                break;
             case CSS::Selector::SimpleSelector::Type::Universal:
                 type_description = "Universal";
                 break;
@@ -378,9 +375,6 @@ void dump_selector(StringBuilder& builder, CSS::Selector const& selector)
                 case CSS::Selector::SimpleSelector::PseudoClass::Type::Active:
                     pseudo_class_description = "Active";
                     break;
-                case CSS::Selector::SimpleSelector::PseudoClass::Type::None:
-                    pseudo_class_description = "None";
-                    break;
                 case CSS::Selector::SimpleSelector::PseudoClass::Type::Root:
                     pseudo_class_description = "Root";
                     break;
@@ -479,9 +473,6 @@ void dump_selector(StringBuilder& builder, CSS::Selector const& selector)
             if (simple_selector.type == CSS::Selector::SimpleSelector::Type::PseudoElement) {
                 char const* pseudo_element_description = "";
                 switch (simple_selector.pseudo_element()) {
-                case CSS::Selector::PseudoElement::None:
-                    pseudo_element_description = "NONE";
-                    break;
                 case CSS::Selector::PseudoElement::Before:
                     pseudo_element_description = "before";
                     break;
@@ -507,9 +498,6 @@ void dump_selector(StringBuilder& builder, CSS::Selector const& selector)
                 char const* attribute_match_type_description = "";
 
                 switch (attribute.match_type) {
-                case CSS::Selector::SimpleSelector::Attribute::MatchType::None:
-                    attribute_match_type_description = "NONE";
-                    break;
                 case CSS::Selector::SimpleSelector::Attribute::MatchType::HasAttribute:
                     attribute_match_type_description = "HasAttribute";
                     break;