[gardening] Mark LibTest/io/FileSystemCreateEvent/isDirectory_A01_t06 flaky
[gardening] Mark LibTest/io/FileSystemCreateEvent/isDirectory_A01_t06 flaky

The test makes assumptions about file system events firing synchronously with file system operations

Issue https://github.com/dart-lang/co19/issues/186

Change-Id: Ic54782662e453c240d92113d25f7a6897b268130
Reviewed-on: https://dart-review.googlesource.com/c/85684
Reviewed-by: Daco Harkes <930cbae0ca77f1954c53e32620d89cfcca318f00@google.com>
Commit-Queue: Daco Harkes <930cbae0ca77f1954c53e32620d89cfcca318f00@google.com>
Auto-Submit: Daco Harkes <930cbae0ca77f1954c53e32620d89cfcca318f00@google.com>

dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk