`test/instances/instance_inspection_canary_test.dart: type and fields` failing

[bkonyi]

Started failing in today's webdev daily test run.

  [FINEST] ExpressionEvaluator: Evaluated "instance" to "{type: object, className: main.MainClass.new, description: main.MainClass.new, objectId: -8724672307244750059.1.342}"
  Expected: {'_field': 1, 'field': 2}
    Actual: {}
     Which: has different length and is missing map key '_field'
  
  package:matcher                                               expect
  test/instances/common/instance_inspection_common.dart 141:11  runTests.<fn>.<fn>.<fn>.<fn>
  ===== asynchronous gap ===========================
  test/instances/common/test_inspector.dart 36:7                TestInspector.onBreakPoint
  ===== asynchronous gap ===========================
  test/instances/common/instance_inspection_common.dart 122:9   runTests.<fn>.<fn>.<fn>
  Expected: {'_field': 1, 'field': 2}
    Actual: {}
     Which: has different length and is missing map key '_field'

FYI @biggs0125 @nshahan @Markzipan

[biggs0125]

Seems like this is caused by this line I just added to the DDC debug logic: https://github.com/dart-lang/sdk/blob/main/sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/debugger.dart#L356

It seems like some parts of the inspector are assuming the presence of a length means the object is a List/Map/Set and not fetching the fields from it.