LibWeb: Return FlyString from CSS::Parser::Token::ident

Instead of a StringView. This allows us to preserve the nice O(1) string
compare property of FlyString, and not needing to allocate when one is
needed.

Ideally all other places in Token should have similar changes done, but
to prevent a huge amount of churn, just change ident for now.

Userland/Libraries/LibWeb/CSS/Parser/MediaParsing.cpp

@@ -261,12 +261,12 @@ Optional<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>&
                 return MediaFeatureName { MediaFeatureName::Type::Normal, id.value() };
             }
 
-            if (allow_min_max_prefix && (name.starts_with("min-"sv, CaseSensitivity::CaseInsensitive) || name.starts_with("max-"sv, CaseSensitivity::CaseInsensitive))) {
-                auto adjusted_name = name.substring_view(4);
+            if (allow_min_max_prefix && (name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) || name.starts_with_bytes("max-"sv, CaseSensitivity::CaseInsensitive))) {
+                auto adjusted_name = name.bytes_as_string_view().substring_view(4);
                 if (auto id = media_feature_id_from_string(adjusted_name); id.has_value() && media_feature_type_is_range(id.value())) {
                     transaction.commit();
                     return MediaFeatureName {
-                        name.starts_with("min-"sv, CaseSensitivity::CaseInsensitive) ? MediaFeatureName::Type::Min : MediaFeatureName::Type::Max,
+                        name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) ? MediaFeatureName::Type::Min : MediaFeatureName::Type::Max,
                         id.value()
                     };
                 }

Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp

@@ -1574,7 +1574,7 @@ CSSRule* Parser::convert_to_rule(NonnullRefPtr<Rule> rule)
             auto token = token_stream.next_token();
             Optional<DeprecatedString> prefix = {};
             if (token.is(Token::Type::Ident)) {
-                prefix = token.token().ident();
+                prefix = token.token().ident().bytes_as_string_view();
                 token_stream.skip_whitespace();
                 token = token_stream.next_token();
             }
@@ -2446,7 +2446,7 @@ Optional<Color> Parser::parse_color(ComponentValue const& component_value)
         else {
             if (!cv.is(Token::Type::Ident))
                 return {};
-            serialization = cv.token().ident();
+            serialization = cv.token().ident().bytes_as_string_view();
         }
 
         // 4. If serialization does not consist of three or six characters, return an error.
@@ -4178,7 +4178,7 @@ RefPtr<StyleValue> Parser::parse_font_family_value(TokenStream<ComponentValue>&
                 (void)tokens.next_token(); // Comma
                 continue;
             }
-            current_name_parts.append(tokens.next_token().token().ident());
+            current_name_parts.append(tokens.next_token().token().ident().bytes_as_string_view());
             continue;
         }
 
@@ -4270,7 +4270,7 @@ CSSRule* Parser::parse_font_face_rule(TokenStream<ComponentValue>& tokens)
                         had_syntax_error = true;
                         break;
                     }
-                    font_family_parts.append(part.token().ident());
+                    font_family_parts.append(part.token().ident().bytes_as_string_view());
                     continue;
                 }
 
@@ -6800,7 +6800,7 @@ bool Parser::expand_variables(DOM::Element& element, Optional<Selector::PseudoEl
         if (!custom_property_name_token.is(Token::Type::Ident))
             return false;
         auto custom_property_name = custom_property_name_token.token().ident();
-        if (!custom_property_name.starts_with("--"sv))
+        if (!custom_property_name.bytes_as_string_view().starts_with("--"sv))
             return false;
 
         // Detect dependency cycles. https://www.w3.org/TR/css-variables-1/#cycles

Userland/Libraries/LibWeb/CSS/Parser/SelectorParsing.cpp

@@ -729,10 +729,10 @@ Optional<Selector::SimpleSelector::ANPlusBPattern> Parser::parse_a_n_plus_b_patt
         if (!value.is(Token::Type::Ident))
             return false;
         auto ident = value.token().ident();
-        if (!ident.starts_with("n-"sv, CaseSensitivity::CaseInsensitive))
+        if (!ident.starts_with_bytes("n-"sv, CaseSensitivity::CaseInsensitive))
             return false;
-        for (size_t i = 2; i < ident.length(); ++i) {
-            if (!is_ascii_digit(ident[i]))
+        for (size_t i = 2; i < ident.bytes_as_string_view().length(); ++i) {
+            if (!is_ascii_digit(ident.bytes_as_string_view()[i]))
                 return false;
         }
         return true;
@@ -741,12 +741,12 @@ Optional<Selector::SimpleSelector::ANPlusBPattern> Parser::parse_a_n_plus_b_patt
         if (!value.is(Token::Type::Ident))
             return false;
         auto ident = value.token().ident();
-        if (!ident.starts_with("-n-"sv, CaseSensitivity::CaseInsensitive))
+        if (!ident.starts_with_bytes("-n-"sv, CaseSensitivity::CaseInsensitive))
             return false;
-        if (ident.length() == 3)
+        if (ident.bytes_as_string_view().length() == 3)
             return false;
-        for (size_t i = 3; i < ident.length(); ++i) {
-            if (!is_ascii_digit(ident[i]))
+        for (size_t i = 3; i < ident.bytes_as_string_view().length(); ++i) {
+            if (!is_ascii_digit(ident.bytes_as_string_view()[i]))
                 return false;
         }
         return true;
@@ -844,7 +844,7 @@ Optional<Selector::SimpleSelector::ANPlusBPattern> Parser::parse_a_n_plus_b_patt
     }
     // <dashndashdigit-ident>
     if (is_dashndashdigit_ident(first_value)) {
-        auto maybe_b = first_value.token().ident().substring_view(2).to_int();
+        auto maybe_b = first_value.token().ident().bytes_as_string_view().substring_view(2).to_int();
         if (maybe_b.has_value()) {
             transaction.commit();
             return Selector::SimpleSelector::ANPlusBPattern { -1, maybe_b.value() };
@@ -957,7 +957,7 @@ Optional<Selector::SimpleSelector::ANPlusBPattern> Parser::parse_a_n_plus_b_patt
 
     // '+'?† <ndashdigit-ident>
     if (is_ndashdigit_ident(first_after_plus)) {
-        auto maybe_b = first_after_plus.token().ident().substring_view(1).to_int();
+        auto maybe_b = first_after_plus.token().ident().bytes_as_string_view().substring_view(1).to_int();
         if (maybe_b.has_value()) {
             transaction.commit();
             return Selector::SimpleSelector::ANPlusBPattern { 1, maybe_b.value() };

Userland/Libraries/LibWeb/CSS/Parser/Token.h

@@ -59,10 +59,10 @@ public:
     Type type() const { return m_type; }
     bool is(Type type) const { return m_type == type; }
 
-    StringView ident() const
+    FlyString const& ident() const
     {
         VERIFY(m_type == Type::Ident);
-        return m_value.bytes_as_string_view();
+        return m_value;
     }
 
     StringView function() const