The experimental expression evaluation feature supports evaluating closures, but causes an error displayed in VSCode debug console (see image below).

Repro steps

• Install flutter
• Use flutter's example/hello_world, set a breakpoint in
  flutter/packages/flutter/lib/src/widgets/binding.dart:921
• Add --web-enable-expression-evaluation flag to dart args in launch.json:

   {
       "version": "0.2.0",
       "configurations": [
           {
               "name": "Flutter",
               "request": "launch",
               "type": "dart",
               "args": ["--web-enable-expression-evaluation"],
           }
       ]
   }

• hover over attachRootWidget

Actual behavior

• native function text without a body is displayed in pop-up box, and appears to not have a lot of useful information
• Unknown instance kind: closure error appears in the debug console

Expected behavior

• some useful representation of the function displayed, for example:
  • maybe full text (if small)
  • or a signature and a few lines
  • or no popup at all
• no error in display window