This reverts commit b75057b687.
Reason for revert: Caused some failures on app-jit builders
Original change's description:
> [vm/concurrency] Introduce concept of Isolate Groups
>
> An Isolate Group (IG) is a collection of isolates which were spawned from the
> same source. This allows the VM to:
>
> * have a guarantee that all isolates within one IG can safely exchange
> structured objects (currently we rely on embedder for this
> guarantee)
>
> * hot-reload all isolates together (currently we only reload one
> isolate, leaving same-source isolates in inconsistent state)
>
> * make a shared heap for all isolates from the same IG, which paves
> the way for faster communication and sharing of immutable objects.
>
> All isolates within one IG will share the same IsolateGroupSource.
>
> **Embedder changes**
>
> This change makes breaking embedder API changes to support this new
> concept of Isolate Groups: The existing isolate lifecycle callbacks
> given to Dart_Initialize will become Isolate Group lifecycle callbacks.
> A new callback `initialize_isolate` callback will be added which can
> initialize a new isolate within an existing IG.
>
> Existing embedders can be updated by performing the following renames
>
> Dart_CreateIsolate -> Dart_CreateIsolateGroup
> Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
> Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
> Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
> Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
> Dart_IsolateData -> Dart_IsolateGroupData
> Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
> Dart_InitializeParams.create -> Dart_InitializeParams.create_group
> Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
> Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
>
> By default `Isolate.spawn` will cause the creation of a new IG.
>
> Though an embedder can opt-into supporting multiple isolates within one IG by
> providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
> The responsibility of this new callback is to initialize an existing
> isolate (which was setup by re-using source code from the spawning
> isolate - i.e. the one which used `Isolate.spawn`) by setting native
> resolvers, initializing global state, etc.
>
> Issue https://github.com/dart-lang/sdk/issues/36648
> Issue https://github.com/dart-lang/sdk/issues/36097
>
> Change-Id: I82437ac017ca33018d45e02f353b0672db155f6a
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105241
> Commit-Queue: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Alexander Aprelev <aam@google.com>
TBR=kustermann@google.com,aam@google.com,rmacnak@google.com
Change-Id: Ibd90992a01d61188f27b445c21532e0c46f996ea
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107405
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
b2171f16f1