transfer filtering

[cometkim]

trying sandboxing a webapp using WorkerDOM. Currently, the <script> attached by the worker thread is executed on the host, so I had to add a filter rule to prevent this.

https://github.com/ampproject/worker-dom/blob/da975ce/src/main-thread/commands/child-list.ts#L38

- if (newNode) {
+ if (filter(newNode)) {

But I think this is too close to implementation detail.

Is there a good place to configure when installing WorkerDOM?