Update API docs and demos for recent worker improvements.

Because:

1. We have no control over the 3rd-party inflate/deflate libraries. We can
therefore not guarantee that GC will always work.
2. In case we want to use a different implementation for worker allocation,
e.g. pooling (e.g. to deal with the per-origin # of Workers constraint),
then we do need proper recounting and cannot rely on the GC any more.