Fix logical error in TimePickerDialog - the RenderObject forgets to update fields

[fzyzcjy]

Close #112038. Please see description there.

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[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat (don't just cc him here, he won't see it! He's on Discord!).

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

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[jonahwilliams]

LGTM

[Hixie]

would be good to have a test for this.

[jonahwilliams]

Ahh my bad, I should have asked for a test for this one

[fzyzcjy]

@Hixie I have tried but failed, that is why this one has no tests though others have :/ It is so deep that it is hard to construct a test, without relaxing the code visibility of the widget/renderobjects.

(I forget to ask for a test-preempt as well)

[fzyzcjy]

@Hixie So shall I relax the code visibility of the widgets and render objects (i.e. change from private to public) in order to have a test? If so I will add it.

[Hixie]

Tests can actually get to the private classes, they just can't use the private class name. You can cast the render object to dynamic and can call things on it blindly.

[fzyzcjy]

@Hixie Thanks, but the problem is I cannot construct a _CupertinoDialogRenderWidget object. All its current usages does not cause this bug (but future usages may do), while this is a logical bug indeed (since by definition updateRenderObject should update the fields).

[Hixie]

Ah, I see. Yeah, that's unfortunate. Probably fine to skip the test for now then.

test-exempt: not technically changing actual behaviour.