``` before
$ dart isolate_exit_pause_time_test.dart
.Min(RunTimeRaw): 0.001 ms.
.Avg(RunTimeRaw): 212.399592 ms.
.Percentile50(RunTimeRaw): 49.055 ms.
.Percentile90(RunTimeRaw): 809.049 ms.
.Percentile95(RunTimeRaw): 1009.049 ms.
.Percentile99(RunTimeRaw): 1169.049 ms.
.Max(RunTimeRaw): 1208.049 ms.
```
``` after
$ dart isolate_exit_pause_time_test.dart
.Min(RunTimeRaw): 0.001 ms.
.Avg(RunTimeRaw): 53.87510125 ms.
.Percentile50(RunTimeRaw): 8.05 ms.
.Percentile90(RunTimeRaw): 174.005 ms.
.Percentile95(RunTimeRaw): 217.975 ms.
.Percentile99(RunTimeRaw): 275.033 ms.
.Max(RunTimeRaw): 314.033 ms.
```
Remaining latency after the change is due to large root set formed by pointers_to_verify_at_exit_ that have to be visited during GC.
Fixes https://github.com/dart-lang/sdk/issues/49050
TEST=ci
Change-Id: I1ed7af017f80890900b137a1514e5ffdeb63f53f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/246482
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
Alexander Aprelev
f681734aef