This reverts commit 5a32d8bc7c.
Reason for revert: DartIsolateTest.CanCreateServiceIsolate flutter engine unit test hangs on Windows.
Original change's description:
> [vm] Simplify implementation of native ports
>
> This CL turns native ports into a thin abstraction over underlying
> thread pool instead of building them as full fledged MessageHandler.
>
> This allows to easily implement a variation of native ports which can
> handle messages concurrently with the given degree of concurrency.
> This type of port can be used to greatly simplify implementation of
> IOService - which previously had to do its own concurrency management
> on top of "single threaded" native ports. This capability is exposed
> as `Dart_NewConcurrentNativePort` API.
>
> The new implementation is in general much cleaner then the old one
> with one exception: `Dart_CloseNativePort` API has unfortunate design
> where underlying message handler is destroyed asynchronously and
> `Dart_CloseNativePort` returns immediately without waiting for pending
> tasks to complete. Implementing this on top of `ThreadPool` requires
> some changes to thread pool implementation.
>
> Issue https://github.com/dart-lang/sdk/issues/55844
>
> TEST=ci
>
> Change-Id: I062040ff233e93962ae93684e9b044d8facdaffc
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/382163
> Commit-Queue: Slava Egorov <vegorov@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
Change-Id: I7de27793a54072e974bf1a9f17a07c12159a202d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/384481
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Slava Egorov
120dac365d