Remove unneceesary `rm`
Remove unneceesary `rm`

The write_empty_coverage file seems to wipe out this folder anyway, so this was pointless and fails on Windows.

Fixes #720.

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