DOM: Implement the `take()` Observable operator

This CL implements the semantics specified in
https://wicg.github.io/observable/#dom-observable-take.

See https://github.com/WICG/observable/pull/113

.

For WPTs:
Co-authored-by:  <ben@benlesh.com>

R=masonf@chromium.org

Bug: 40282760
Change-Id: Iaaa957c20db8df54619b65d98ca54385d5ee79a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5292297


Reviewed-by: Mason Freed <masonf@chromium.org>
Commit-Queue: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1263804}