Dart 2 runtime failures in tests

[keertip]

Running tests in Dart 2 mode, see the following failure

00:02 +0 -2: RecordingProcessManager run [E]
type 'List' is not a subtype of type 'List' where
List is from dart:core
List is from dart:core
String is from dart:core

package:process/src/record_replay/common.dart 15:6 sanitize
package:process/src/record_replay/recording_process_manager.dart 147:37 RecordingProcessManager.run
===== asynchronous gap ===========================
dart:async _Completer.completeError
package:process/src/record_replay/recording_process_manager.dart RecordingProcessManager.run
===== asynchronous gap ===========================
dart:async _asyncThenWrapperHelper
package:process/src/record_replay/recording_process_manager.dart RecordingProcessManager.run
../../tmp/archives/third_party/dart/process/test/record_test.dart 65:25 main..
===== asynchronous gap ===========================
dart:async new Future.microtask
../../process/test/record_test.dart 63:17 main..

[keertip]

/cc @srawlins

[stuartmorgan]

Closing as obsolete; tests are passing.