Fix "Rerun Last Run"
Fix "Rerun Last Run"

VS Code ends the run when `runHandler` finishes, so this was being counted as a separate run (and a VS Code bug means they don't currently work for the Tests: Rerun Last Run command).

Fixes #3849.

Dart-Code/Dart-Code,Dart-Code/Dart-Code,Dart-Code/Dart-Code,Dart-Code/Dart-Code,Dart-Code/Dart-Code