refactor: smallify all the things

[benlesh]

Going through, operator by operator, and making them smaller. Centralizing on a new type called OperatorSubscriber that enables most behaviors fairly cleanly and concisely.
WIP

Will show stats when finished.

Progress Update 9/17

BEFORE: 93KB

AFTER: 59KB (63% of the original size)
AFTER: 57KB (61% of the original size)

Review Checklist:

Reviewed files:

Check only files that have been reviewed and have no issues. If there are issues with a review, add a link to the review to the listed file.

• api_guard/dist/types/index.d.ts
• api_guard/dist/types/operators/index.d.ts
• spec/observables/IteratorObservable-spec.ts
• spec/observables/fromEvent-spec.ts refactor: smallify all the things #5729 (review)
• spec/operators/debounce-spec.ts
• spec/operators/delay-spec.ts
• spec/operators/expand-spec.ts
• spec/operators/find-spec.ts
• spec/operators/groupBy-spec.ts
• spec/operators/map-spec.ts
• spec/operators/observeOn-spec.ts
• spec/operators/scan-spec.ts
• spec/operators/skipLast-spec.ts
• spec/operators/take-spec.ts
• spec/operators/takeLast-spec.ts
• spec/operators/takeWhile-spec.ts
• spec/operators/windowTime-spec.ts
• spec/subjects/AsyncSubject-spec.ts
• src/internal/AsyncSubject.ts
• src/internal/BehaviorSubject.ts
• src/internal/Notification.ts
• src/internal/Observable.ts
• src/internal/ReplaySubject.ts
• src/internal/Subject.ts refactor: smallify all the things #5729 (review)
• src/internal/SubjectSubscription.ts
• src/internal/Subscriber.ts
• src/internal/Subscription.ts
• src/internal/innerSubscribe.ts
• src/internal/observable/ConnectableObservable.ts
• src/internal/observable/concat.ts
• src/internal/observable/from.ts
• src/internal/observable/fromEvent.ts
• src/internal/observable/fromIterable.ts
• src/internal/observable/fromObservable.ts
• src/internal/observable/fromPromise.ts
• src/internal/observable/generate.ts
• src/internal/observable/merge.ts
• src/internal/observable/partition.ts
• src/internal/observable/race.ts
• src/internal/operators/OperatorSubscriber.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/audit.ts
• src/internal/operators/buffer.ts
• src/internal/operators/bufferCount.ts
• src/internal/operators/bufferTime.ts
• src/internal/operators/bufferToggle.ts
• src/internal/operators/bufferWhen.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/catchError.ts
• src/internal/operators/concat.ts
• src/internal/operators/concatWith.ts
• src/internal/operators/count.ts
• src/internal/operators/debounce.ts
• src/internal/operators/debounceTime.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/defaultIfEmpty.ts
• src/internal/operators/delay.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/delayWhen.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/dematerialize.ts
• src/internal/operators/distinct.ts
• src/internal/operators/distinctUntilChanged.ts
• src/internal/operators/every.ts
• src/internal/operators/exhaust.ts
• src/internal/operators/exhaustMap.ts
• src/internal/operators/expand.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/filter.ts
• src/internal/operators/finalize.ts
• src/internal/operators/find.ts
• src/internal/operators/findIndex.ts
• src/internal/operators/groupBy.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/ignoreElements.ts
• src/internal/operators/index.ts
• src/internal/operators/isEmpty.ts
• src/internal/operators/map.ts
• src/internal/operators/mapTo.ts
• src/internal/operators/materialize.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/mergeMap.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/mergeScan.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/mergeWith.ts
• src/internal/operators/multicast.ts
• src/internal/operators/observeOn.ts
• src/internal/operators/pairwise.ts
• src/internal/operators/partition.ts
• src/internal/operators/raceWith.ts
• src/internal/operators/reduce.ts
• src/internal/operators/refCount.ts
• src/internal/operators/repeat.ts
• src/internal/operators/repeatWhen.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/retryWhen.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/sample.ts
• src/internal/operators/sampleTime.ts
• src/internal/operators/scan.ts
• src/internal/operators/sequenceEqual.ts
• src/internal/operators/single.ts
• src/internal/operators/skip.ts
• src/internal/operators/skipLast.ts
• src/internal/operators/skipUntil.ts
• src/internal/operators/skipWhile.ts
• src/internal/operators/subscribeOn.ts
• src/internal/operators/switchMap.ts
• src/internal/operators/take.ts
• src/internal/operators/takeLast.ts
• src/internal/operators/takeUntil.ts
• src/internal/operators/takeWhile.ts
• src/internal/operators/throttle.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/throttleTime.ts
• src/internal/operators/throwIfEmpty.ts
• src/internal/operators/timeout.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/window.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/windowCount.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/windowTime.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/windowToggle.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/windowWhen.ts refactor: smallify all the things #5729 (review)
• src/internal/operators/withLatestFrom.ts refactor: smallify all the things #5729 (review)
• src/internal/scheduler/AsyncAction.ts
• src/internal/util/arrRemove.ts
• src/internal/util/lift.ts
• src/internal/util/not.ts
• src/internal/util/subscribeTo.ts
• src/operators/index.ts

[benlesh]

@cartant and @jayphelps ... I think I've addressed all of your comments.

I've unified on an approach for freeing up resources like buffered values, I think... basically, a returned function from the lift is a terse way to add a teardown to the destination subscriber. This ensures that the resource will be freed regardless of source (or inner) completion or error, or destination unsubscription. It could delay the release of those resources in some cases, so things will still have to be addressed on a case-by-case basis. But over all it looks like this:

return (source: Observable<T>) => lift(source, function(this: Subscriber<R>, source: Observable<T>) {
   const subscriber = this;
   /* stuff here */

   // Additional teardown
   return () => {
      buffer = null!
   };
});

This is equivalent to making the last line: subscriber.add(() => buffer = null!).

[cartant]

🚢