Flaky VM service test: pause_on_start_and_exit_test

[fsc8000]

This test sometimes fails with the following error. The timestamp of the pause event seems to be off by one ms. @turnidge @johnmccutchan

https://build.chromium.org/p/client.dart/builders/vm-linux-release-ia32-be/builds/12471/steps/vm%20tests/logs/stdio

=== Failure summary:


FAILED: none-vm release_ia32 service/pause_on_start_and_exit_test
Expected: Pass 
Actual: RuntimeError
CommandOutput[vm]:

stdout:
** Launching out/ReleaseIA32/dart --trace-service --trace-service-verbose --pause-isolates-on-start --pause-isolates-on-exit --error_on_bad_type --error_on_bad_override --ignore-unrecognized-flags --package-root=out/ReleaseIA32/packages/ --enable-vm-service:0 /mnt/data/b/build/slave/vm-linux-release-ia32-be/build/sdk/runtime/observatory/tests/service/pause_on_start_and_exit_test.dart
vm-service: Booting dart:vmservice library.
vm-service: Registering running isolates.
vm-service: Isolate pause_on_start_and_exit_test.dart$main-511212762 511212762 registered.
** Signaled to run test queries on 36780
Observatory listening on http://127.0.0.1:36780
Loading VM...
vm-service: starting stream 'VM'
vm-service: starting stream 'Isolate'
vm-service: starting stream 'Debug'
vm-service: starting stream '_Graph'
[+287ms] Isolate vm-service processing service request getVM
[+288ms] Isolate vm-service processed service request getVM (47us)
Done loading VM
vm-service: Pushing ServiceEvent(isolate='pause_on_start_and_exit_test.dart$main-511212762', kind='IsolateRunnable') to stream Isolate
[+300ms] Isolate pause_on_start_and_exit_test.dart$main-511212762 processing service request getIsolate
[+300ms] Isolate pause_on_start_and_exit_test.dart$main-511212762 processed service request getIsolate (525us)
vm-service: Pushing ServiceEvent(isolate='pause_on_start_and_exit_test.dart$main-511212762', kind='PauseStart') to stream Debug
Running pause_on_start_and_exit_test.dart [1/1]
Getting stream...
Subscribing...
Subscribed.  Pause event is ServiceEvent(owner='isolates/511212762', kind='PauseStart', time=2016-05-17 03:30:27.308)
Subscription cancelled.
Done waiting for pause event.
** Killing script
Unexpected exception in service tests: Expected: <1463481027309>
  Actual: <1463481027308>
 #0      DefaultFailureHandler.fail (package:unittest/src/matcher/expect.dart:117:5)
#1      DefaultFailureHandler.failMatch (package:unittest/src/matcher/expect.dart:121:5)
#2      expect (package:unittest/src/matcher/expect.dart:95:20)
#3      tests.<anonymous closure>.<<anonymous closure>_async_body> (file:///mnt/data/b/build/slave/vm-linux-release-ia32-be/build/sdk/runtime/observatory/tests/service/pause_on_start_and_exit_test.dart:51:3)
#4      _asyncThenWrapperHelper.<anonymous closure> (dart:async-patch/async_patch.dart:27)
#5      _rootRunUnary (dart:async/zone.dart:958)
#6      _CustomZone.runUnary (dart:async/zone.dart:837)
#7      _FutureListener.handleValue (dart:async/future_impl.dart:131)
#8      _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:637)
#9      _Future._propagateToListeners (dart:async/future_impl.dart:667)
#10     _Future._completeWithValue (dart:async/future_impl.dart:477)
#11     _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:528)
#12     _rootRun (dart:async/zone.dart:950)
#13     _CustomZone.run (dart:async/zone.dart:826)
#14     _CustomZone.runGuarded (dart:async/zone.dart:724)
#15     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:751)
#16     _microtaskLoop (dart:async/schedule_microtask.dart:41)
#17     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#18     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:96)
#19     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:149)



stderr:
Unhandled exception:
Expected: <1463481027309>
  Actual: <1463481027308>

#0      DefaultFailureHandler.fail (package:unittest/src/matcher/expect.dart:117:5)
#1      DefaultFailureHandler.failMatch (package:unittest/src/matcher/expect.dart:121:5)
#2      expect (package:unittest/src/matcher/expect.dart:95:20)
#3      tests.<anonymous closure>.<<anonymous closure>_async_body> (file:///mnt/data/b/build/slave/vm-linux-release-ia32-be/build/sdk/runtime/observatory/tests/service/pause_on_start_and_exit_test.dart:51:3)
#4      _asyncThenWrapperHelper.<anonymous closure> (dart:async-patch/async_patch.dart:27)
#5      _rootRunUnary (dart:async/zone.dart:958)
#6      _CustomZone.runUnary (dart:async/zone.dart:837)
#7      _FutureListener.handleValue (dart:async/future_impl.dart:131)
#8      _Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:637)
#9      _Future._propagateToListeners (dart:async/future_impl.dart:667)
#10     _Future._completeWithValue (dart:async/future_impl.dart:477)
#11     _Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:528)
#12     _rootRun (dart:async/zone.dart:950)
#13     _CustomZone.run (dart:async/zone.dart:826)
#14     _CustomZone.runGuarded (dart:async/zone.dart:724)
#15     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:751)
#16     _microtaskLoop (dart:async/schedule_microtask.dart:41)
#17     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#18     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:96)
#19     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:149)


Command[vm]: DART_CONFIGURATION=ReleaseIA32 out/ReleaseIA32/dart --error_on_bad_type --error_on_bad_override --ignore-unrecognized-flags --package-root=out/ReleaseIA32/packages/ /mnt/data/b/build/slave/vm-linux-release-ia32-be/build/sdk/runtime/observatory/tests/service/pause_on_start_and_exit_test.dart
Took 0:00:00.630038

Short reproduction command (experimental):
    python tools/test.py -mrelease -aia32 --write-debug-log --write-test-outcome-log --copy-coredumps --exclude-suite pkg -t60 service/pause_on_start_and_exit_test