LibWeb/CSS: Maintain original form of media-feature ranges

Previously, for `foo < 30px` ranges, we'd flip them and store them as
`30px > foo` instead. That worked fine, but means the serialization is
wrong. So instead, keep them in their original form.

I experimented with giving Range two optional sub-structs instead of 4
optional members, thinking it would be smaller - but it's actually
larger, because the two Optional<Comparison>s fit snugly together. So,
the slightly-goofy all-Optionals remains.

This gets us 2 WPT passes that I'm aware of.

Libraries/LibWeb/CSS/MediaQuery.cpp

@@ -82,10 +82,14 @@ String MediaFeature::to_string() const
         return MUST(String::formatted("max-{}: {}", string_from_media_feature_id(m_id), value().to_string()));
     case Type::Range: {
         auto& range = this->range();
-        if (!range.right_comparison.has_value())
-            return MUST(String::formatted("{} {} {}", range.left_value.to_string(), comparison_string(range.left_comparison), string_from_media_feature_id(m_id)));
+        StringBuilder builder;
+        if (range.left_comparison.has_value())
+            builder.appendff("{} {} ", range.left_value->to_string(), comparison_string(*range.left_comparison));
+        builder.append(string_from_media_feature_id(m_id));
+        if (range.right_comparison.has_value())
+            builder.appendff(" {} {}", comparison_string(*range.right_comparison), range.right_value->to_string());
 
-        return MUST(String::formatted("{} {} {} {} {}", range.left_value.to_string(), comparison_string(range.left_comparison), string_from_media_feature_id(m_id), comparison_string(*range.right_comparison), range.right_value->to_string()));
+        return builder.to_string_without_validation();
     }
     }
 
@@ -137,12 +141,15 @@ MatchResult MediaFeature::evaluate(HTML::Window const* window) const
 
     case Type::Range: {
         auto const& range = this->range();
-        if (auto const left_result = compare(*window, range.left_value, range.left_comparison, queried_value); left_result != MatchResult::True)
+        if (range.left_comparison.has_value()) {
+            if (auto const left_result = compare(*window, *range.left_value, *range.left_comparison, queried_value); left_result != MatchResult::True)
                 return left_result;
+        }
 
-        if (range.right_comparison.has_value())
+        if (range.right_comparison.has_value()) {
             if (auto const right_result = compare(*window, queried_value, *range.right_comparison, *range.right_value); right_result != MatchResult::True)
                 return right_result;
+        }
 
         return MatchResult::True;
     }

Libraries/LibWeb/CSS/MediaQuery.h

@@ -132,7 +132,6 @@ public:
         return adopt_own(*new MediaFeature(Type::MaxValue, id, move(value)));
     }
 
-    // Corresponds to `<mf-range>` grammar, with a single comparison
     static NonnullOwnPtr<MediaFeature> half_range(MediaFeatureValue value, Comparison comparison, MediaFeatureID id)
     {
         return adopt_own(*new MediaFeature(Type::Range, id,
@@ -141,6 +140,14 @@ public:
                 .left_comparison = comparison,
             }));
     }
+    static NonnullOwnPtr<MediaFeature> half_range(MediaFeatureID id, Comparison comparison, MediaFeatureValue value)
+    {
+        return adopt_own(*new MediaFeature(Type::Range, id,
+            Range {
+                .right_comparison = comparison,
+                .right_value = move(value),
+            }));
+    }
 
     // Corresponds to `<mf-range>` grammar, with two comparisons
     static NonnullOwnPtr<MediaFeature> range(MediaFeatureValue left_value, Comparison left_comparison, MediaFeatureID id, Comparison right_comparison, MediaFeatureValue right_value)
@@ -168,8 +175,8 @@ private:
     };
 
     struct Range {
-        MediaFeatureValue left_value;
-        Comparison left_comparison;
+        Optional<MediaFeatureValue> left_value {};
+        Optional<Comparison> left_comparison {};
         Optional<Comparison> right_comparison {};
         Optional<MediaFeatureValue> right_value {};
     };

Libraries/LibWeb/CSS/Parser/MediaParsing.cpp

@@ -274,22 +274,6 @@ OwnPtr<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& to
         return {};
     };
 
-    auto flip = [](MediaFeature::Comparison comparison) {
-        switch (comparison) {
-        case MediaFeature::Comparison::Equal:
-            return MediaFeature::Comparison::Equal;
-        case MediaFeature::Comparison::LessThan:
-            return MediaFeature::Comparison::GreaterThan;
-        case MediaFeature::Comparison::LessThanOrEqual:
-            return MediaFeature::Comparison::GreaterThanOrEqual;
-        case MediaFeature::Comparison::GreaterThan:
-            return MediaFeature::Comparison::LessThan;
-        case MediaFeature::Comparison::GreaterThanOrEqual:
-            return MediaFeature::Comparison::LessThanOrEqual;
-        }
-        VERIFY_NOT_REACHED();
-    };
-
     auto comparisons_match = [](MediaFeature::Comparison a, MediaFeature::Comparison b) -> bool {
         switch (a) {
         case MediaFeature::Comparison::Equal:
@@ -322,7 +306,7 @@ OwnPtr<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& to
                     tokens.discard_whitespace();
                     if (!tokens.has_next_token() && !maybe_value->is_ident()) {
                         transaction.commit();
-                        return MediaFeature::half_range(maybe_value.release_value(), flip(maybe_comparison.release_value()), maybe_name->id);
+                        return MediaFeature::half_range(maybe_name->id, maybe_comparison.release_value(), maybe_value.release_value());
                     }
                 }
             }

Tests/LibWeb/Text/expected/wpt-import/css/css-nesting/nested-declarations-cssom-whitespace.txt

@@ -2,7 +2,6 @@ Harness status: OK
 
 Found 2 tests
 
-1 Pass
-1 Fail
+2 Pass
 Pass	Empty CSSNestedDeclarations do not affect outer serialization
-Fail	Empty CSSNestedDeclarations do not affect outer serialization (nested grouping rule)
+Pass	Empty CSSNestedDeclarations do not affect outer serialization (nested grouping rule)

Tests/LibWeb/Text/expected/wpt-import/css/mediaqueries/prefers-contrast.txt

@@ -2,8 +2,7 @@ Harness status: OK
 
 Found 26 tests
 
-25 Pass
-1 Fail
+26 Pass
 Pass	Should be known: '(prefers-contrast)'
 Pass	Should be known: '(prefers-contrast: no-preference)'
 Pass	Should be known: '(prefers-contrast: more)'
@@ -17,7 +16,7 @@ Pass	Should be parseable: '(prefers-contrast: forced high)'
 Pass	Should be unknown: '(prefers-contrast: forced high)'
 Pass	Should be parseable: '(prefers-contrast: forced low)'
 Pass	Should be unknown: '(prefers-contrast: forced low)'
-Fail	Should be parseable: '(prefers-contrast > increase)'
+Pass	Should be parseable: '(prefers-contrast > increase)'
 Pass	Should be unknown: '(prefers-contrast > increase)'
 Pass	Should be parseable: '(prefers-increased-contrast)'
 Pass	Should be unknown: '(prefers-increased-contrast)'