LibWeb: Stop manually forward-declaring types in CSS Parser.h

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

@@ -28,15 +28,10 @@
 #include <LibWeb/CSS/StyleValue.h>
 #include <LibWeb/CSS/Supports.h>
 #include <LibWeb/CSS/UnicodeRange.h>
+#include <LibWeb/Forward.h>
 
 namespace Web::CSS {
 
-class CSSStyleSheet;
-class CSSRule;
-class CSSStyleRule;
-struct StyleProperty;
-enum class PropertyID;
-
 class ParsingContext {
 public:
     ParsingContext() = default;

Userland/Libraries/LibWeb/Forward.h

@@ -92,6 +92,10 @@ class TransformationStyleValue;
 class UnicodeRange;
 class UnresolvedStyleValue;
 class UnsetStyleValue;
+
+enum class MediaFeatureID;
+enum class PropertyID;
+enum class ValueID;
 }
 
 namespace Web::DOM {