Vet aggressive constructor boilerplate generation.

[pq]

As of the 0.1.24 dev builds completion for children parameters has been improved to include Widget list boilerplate:

(Note that flutter is not yet on this version of the SDK.)

In #463, @mit-mit proposed something more opinionated that would generate the children (and boilerplate) automatically.

Some concerns have been raised that this is too aggressive and it's currently behind a flag.

@InMatrix : what are you thoughts on how to settle this? Should we fold the aggressive behavior into a future user study to collect some feedback? Any other thoughts?

[pq]

Note to self: These two changes revert options. We'll want to add them back or take another tack.

• https://codereview.chromium.org/2924633002/
• https://codereview.chromium.org/2925723002/