Add option to disable DevTools for standalone VM

[bkonyi]

We should provide a --disable-devtools flag to allow for users to prevent DevTools from being served by DDS as some tools / IDEs currently serve their own instances.

[jonahwilliams]

I'm assuming that we're also not going to be starting devtools if we're passing --disable-dart-dev too? Or do we need to add a new flag to the flutter tool bootstrap and other parts of the tool?

[bkonyi]

Yes, that's the case. Also, DevTools will only start if --enable-vm-service or --observe is provided, so even if --disable-dart-dev isn't provided (aside: I'd like to drop that flag at some point since it won't impact startup time for basic runs like dart foo.dart) DevTools won't spawn unless the user explicitly enables the service.

[jonahwilliams]

i believe the concern was less to do with startup time and more to do with making sure programming errors in the tool are surfaced correctly. for example dart program.dart where the program is missing should not print out a warning about there not being a program.dart command

[bkonyi]

i believe the concern was less to do with startup time and more to do with making sure programming errors in the tool are surfaced correctly. for example dart program.dart where the program is missing should not print out a warning about there not being a program.dart command

Oh, well if that's the case, that shouldn't be an issue anymore:

$ dart bad.dart
Error when reading 'bad.dart': No such file or directory.

[jonahwilliams]

cool!