Fix trait parents handling

[NeilKleistGao]

Ignore traits in inheritance clauses correctly and fix translateParents:

:js
trait A
class B() extends A
//│ trait A
//│ class B()
//│ // Prelude
//│ class TypingUnit15 {
//│   #B;
//│   constructor() {
//│   }
//│   get B() {
//│     const outer = this;
//│     if (this.#B === undefined) {
//│       class B extends Object {
//│         constructor() {
//│           super();
//│         }
//│       };
//│       this.#B = (() => Object.freeze(new B()));
//│       this.#B.class = B;
//│     }
//│     return this.#B;
//│   }
//│ }
//│ const typing_unit15 = new TypingUnit15;
//│ globalThis.A = typing_unit15.A;
//│ globalThis.B = typing_unit15.B;
//│ // End of generated code