Register custom property definition from parsed @Property

Author: cdoublev

lib/parse/postprocess.js

@@ -1309,18 +1309,27 @@ function postParsePath(path, node) {
  * - it is missing a declaration for `inherits` or `syntax`
  * - it is missing a declaration for `initial-value` if `syntax` is universal
  * - its declaration for `initial-value` is invalid according to `syntax`
+ *
+ * It appends the property definition in the current global object’s associated
+ * Document's [[registeredPropertySet]] slot.
  */
 function postParseProperty(rule, node) {
-    const { inherits, initialValue, syntax } = rule
+    const { name, inherits, initialValue, syntax } = rule
+    const register = globalThis.document._registeredPropertySet
     if (inherits === undefined || syntax === undefined) {
         return error(node)
     }
     if (syntax === '"*"') {
-        return cssWideKeywords.includes(initialValue) ? error(node) : rule
+        if (cssWideKeywords.includes(initialValue)) {
+            return error(node)
+        }
+        register.push({ inherits, initialValue, name, syntax })
+        return rule
     }
     if (initialValue) {
         const match = parseGrammar(initialValue, syntax.slice(1, -1), '@style')
         if (!isFailure(match) && isComputationallyIndependent(match)) {
+            register.push({ inherits, initialValue, name, syntax })
             return rule
         }
     }