LibJS: Rest parameter in setter functions is a syntax error

Author: https://github.com/linusg
Commit: 1e86379327
Pull-request: https://github.com/SerenityOS/serenity/pull/3809

Libraries/LibJS/Tests/classes/class-errors.js

@@ -70,6 +70,11 @@ describe("syntax errors", () => {
     class A {
       set foo(bar, baz) {
       }
+    }`).not.toEval();
+        expect(`
+    class A {
+      set foo(...bar) {
+      }
     }`).not.toEval();
     });