Meta-issue: Update all code to use optional new/const

[mit-mit]

Tracking issue for updating all our Flutter example code to use optional new/const (now that we are unblocked by the needed lint dart-lang/sdk#32602 being available):

• Flutter.io homepage
• flutter/flutter/examples
• flutter/plugins/examples
• flutter/packages/examples

[a14n]

Actually it's still blocked by dart-lang/sdk#57706 and dart-lang/sdk#57712

[mit-mit]

Thanks, I reactivated dart-lang/sdk#32596

[pq]

@a14n : once the new linter makes it's way into a vended SDK will we be good to make these changes?

[a14n]

I tried to remove unnecessary new/const from flutter codebase and faced a new issue in analyzer dart-lang/sdk#33647

[a14n]

Optional const landed in #19342

[pq]

@a14n: this is fantastic. Remind me the plan for unnecessary_new?

[mit-mit]

@a14n do we have the no new lint?

[a14n]

unnecessary_const landed with #20103 and flutter/plugins#682.
unnecessary_new is waiting for reviews with #20138 and flutter/plugins#701.

[a14n]

unnecessary new/const have been removed from flutter/flutter, flutter/plugins and soon in flutter/packages.
On flutter.io the only remaining place with new/const seems to be in images like on home page at the Fast development section.

[mit-mit]

Excellent! I'll make sure with @maguinis that we get all images updated!

[mit-mit]

Marking flutter/packages done as flutter/packages#4 was merged

[mit-mit]

Assigning to self as only item left is updating images on flutter.io