Observatory evaluation problems

[rakudrama]

I'm on the inspector page for a _List.
The list contains only strings.
evaluate runtimeType gives _List<dynamic>.

Task: count the number of large strings.

Attempt 1:
where((s) => s.length > 1000000).length

The expression is not evaluated:

Unexpected exception:

ServerRpcException(org-dartlang-debug:synthetic_debug_expression:1:16: �[31mError: The getter 'length' isn't defined for the class 'Object?'.
 - 'Object' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'length'.�[39;49m
where((s) => s.length > 1000000).length
               ^^^^^^)

What appears to be happening is that the static context is inside class _List<E>.
So for static checking, E is replace by its bound Object.
While technically correct for code written in the class, this is not helpful in an inspector in the 'same' context.

Attempt 2:
Dart has a dynamic subset, right?
(this as dynamic).where((s) => s.length > 1000000).length

Execution crashes:

Unhandled exception:
type '(dynamic) => dynamic' is not a subtype of type '(dynamic) => bool' of 'test'
#0      List.Eval (:0:19)
#1      Compiler.runCodegenEnqueuer (package:compiler/src/compiler.dart:439:3)
#2      Compiler.generateJavaScriptCode (package:compiler/src/compiler.dart:315:7)
<asynchronous suspension>
#3      Compiler.runInternal (package:compiler/src/compiler.dart:277:7)
<asynchronous suspension>

Attempt 3:
(this as List<dynamic>).where((s) => s.length > 1000000).length
=> 194.

Suggestion: rewrite this to a variable with a type as close as possible to the dynamic type.

/cc @jacob314 I could not figure out how to get devtools to evaluate in this context to see if it has the same problem.
/cc @leafpetersen The dynamic evaluation case in debugging does not work as well as Dart 1.