LibWeb: Make empty media query lists evaluate to true

Author: https://github.com/Gingeh
Commit: 16f2f6aa42
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1611
Reviewed-by: https://github.com/AtkinsSJ ✅

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

@@ -27,6 +27,12 @@ Vector<NonnullRefPtr<MediaQuery>> Parser::parse_a_media_query_list(TokenStream<T
 {
     // https://www.w3.org/TR/mediaqueries-4/#mq-list
 
+    // AD-HOC: Ignore whitespace-only queries
+    // to make `@media {..}` equivalent to `@media all {..}`
+    tokens.skip_whitespace();
+    if (!tokens.has_next_token())
+        return {};
+
     auto comma_separated_lists = parse_a_comma_separated_list_of_component_values(tokens);
 
     AK::Vector<NonnullRefPtr<MediaQuery>> media_queries;
@@ -616,11 +622,6 @@ Optional<MediaFeatureValue> Parser::parse_media_feature_value(MediaFeatureID med
 
 JS::GCPtr<CSSMediaRule> Parser::convert_to_media_rule(Rule& rule)
 {
-    if (rule.prelude().is_empty()) {
-        dbgln_if(CSS_PARSER_DEBUG, "Failed to parse @media rule: Empty prelude.");
-        return {};
-    }
-
     if (!rule.block()) {
         dbgln_if(CSS_PARSER_DEBUG, "Failed to parse @media rule: No block.");
         return {};
@@ -628,8 +629,6 @@ JS::GCPtr<CSSMediaRule> Parser::convert_to_media_rule(Rule& rule)
 
     auto media_query_tokens = TokenStream { rule.prelude() };
     auto media_query_list = parse_a_media_query_list(media_query_tokens);
-    if (media_query_list.is_empty())
-        return {};
 
     auto child_tokens = TokenStream { rule.block()->values() };
     auto parser_rules = parse_a_list_of_rules(child_tokens);