LibWeb/CSS: Disallow :has() and pseudo-elements in :has() when parsing

Author: https://github.com/AtkinsSJ
Commit: 7f803c5c3d
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2340

Tests/LibWeb/Text/input/css/invalid-selector-in-has.html

@@ -5,6 +5,11 @@
     test(() => {
         let selectors = [
             ":has(:yakthonk)",
+            ":has(:not(:yakthonk))",
+            ":has(:has(span))",
+            ":has(:not(:has(span)))",
+            ":has(::before)",
+            ":has(:not(::before))",
         ];
 
         let style = document.getElementById("style");