Getting rid of containers

[nate-thegrate]

This pull request aims to make the Flutter framework more efficient, based on issue #147431.

Going into it, I didn't expect to spend 4 hours updating tests, but apparently find.byType(Container) is very convenient and was used a lot.

[nate-thegrate]

I'm going to try splitting this in half to make it easier to review. We'll see how it goes :)

[goderbauer]

LGTM

[auto-submit]

auto label is removed for flutter/flutter/147432, due to - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label.

[jmagman]

The Google testing failures look related to this PR:

Expected: exactly 2 matching candidates
  Actual: _TypeWidgetFinder:<Found 1 widget with type
"Container": [
            Container(bg: BoxDecoration(color: Color(0xffe8f0fe),
border: Border.all(BorderSide(color: Color(0x00000000))),
borderRadius: BorderRadius.circular(8.0))),
          ]>
   Which: is not enough

and another is failing at

final BuildContext context = tester.element(find.byType(Container));

The following StateError was thrown running a test:
Bad state: No element

@goderbauer could you help with the g3fix, or whatever would be needed to get those tests passing?

[goderbauer]

I am gonna rebase this to kick the checks again.

[goderbauer]

Actually, the github UI isn't allowing me to do a rebase. @nate-thegrate Can you rebase this with the latest main branch?

[nate-thegrate]

Done!

(Edit: that was a merge commit, not a rebase… I'm pretty sure autosubmit does a "squash and merge", so at least the main branch won't be as messy as this PR 🙂)

[nate-thegrate]

Merging per the recent Discord message:

christopherfujino: I am actively investigating autosubmit not working (in #148092 and a thread in this chat)—in the meanwhile, if:

1. all presubmits are green (including tree status)
2. PR has two approving Flutter GitHub org members (including the author if applicable)

Then Flutter GitHub org members should feel empowered to manually merge PRs, until #148092 is fixed.