Fix Isolate scopes in service isolate shutdown

Fix Isolate scopes in service isolate shutdown

We can't shutdown an Isolate inside of a handle scope.

BUG=
R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/8718e005ffa0c5d4b115a6270cf29434172a259d

[zra, 2015-10-30 04:59:20]

zra@google.com changed reviewers:
+ asiva@google.com

[siva, 2015-10-30 15:22:47]

https://codereview.chromium.org/1430783002/diff/1/runtime/vm/service_isolate.cc
File runtime/vm/service_isolate.cc (right):

https://codereview.chromium.org/1430783002/diff/1/runtime/vm/service_isolate....
runtime/vm/service_isolate.cc:367: }
Can we switch this to:

{
   ASSERT(Isolate::Current() == NULL);
   StartIsolateScope start_scope(I);
   {
      Thread* T ...
      .....
      .....
   }
   Dart::ShutdownIsolate();
}

StartIsolateScope itself works fine if the isolate is shutdown under it as there
is a check in Thread::ExitIsolate.

I would like to minimize usage of SwitchIsolateScope in the VM code as far as
possible.

[zra, 2015-10-30 16:48:41]

https://codereview.chromium.org/1430783002/diff/1/runtime/vm/service_isolate.cc
File runtime/vm/service_isolate.cc (right):

https://codereview.chromium.org/1430783002/diff/1/runtime/vm/service_isolate....
runtime/vm/service_isolate.cc:367: }
On 2015/10/30 15:22:47, siva wrote:
> Can we switch this to:
> 
> {
>    ASSERT(Isolate::Current() == NULL);
>    StartIsolateScope start_scope(I);
>    {
>       Thread* T ...
>       .....
>       .....
>    }
>    Dart::ShutdownIsolate();
> }
> 
> StartIsolateScope itself works fine if the isolate is shutdown under it as
there
> is a check in Thread::ExitIsolate.
> 
> I would like to minimize usage of SwitchIsolateScope in the VM code as far as
> possible.

Discussed offline. It is also not possible to do ShutdownIsolate inside of a
StartIsolateScope.

[siva, 2015-10-30 16:50:45]

lgtm

[zra, 2015-10-30 16:57:35]

Committed patchset #1 (id:1) manually as
8718e005ffa0c5d4b115a6270cf29434172a259d (presubmit successful).