Support reduceMotion accessibility feature in MediaQuery

[cbracken]

Exposes the platform's "Reduce Motion" accessibility setting through MediaQueryData, so widgets can react to it with proper dependency tracking instead of reading it ad hoc off the platform dispatcher.

The reduceMotion flag tracking the iOS "Reduce Motion" setting already exists at the engine layer as
dart:ui.AccessibilityFeatures.reduceMotion, but it was never surfaced on MediaQueryData. This mirrors the existing disableAnimations support, which corresponds to Android's "Remove animations" setting.

Unlike disableAnimations, reduceMotion is not consulted by framework-level animation APIs such as AnimationController. It is intended for widgets that want to tone down or replace non-essential motion, for example, by substituting a cross-fade for a slide.

No engine or SemanticsBinding changes are required: as with disableAnimations, MediaQueryData reads reduceMotion directly from platformDispatcher.accessibilityFeatures, and FakeAccessibilityFeatures already supports the flag.

Issue: #4827
Issue: #65874

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
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• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
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[gemini-code-assist]

Code Review

This pull request introduces the reduceMotion accessibility setting to MediaQueryData and MediaQuery, allowing widgets to adapt to platform requests for reduced motion. It includes updates to constructor initialization, copying, equality checks, and static helper methods, along with corresponding unit tests. The reviewer pointed out that several methods in MediaQueryData that return new instances (such as removeViewPadding, padOuter, and removeDisplayFeatures) were not updated to copy the new reduceMotion property, which would cause the setting to be lost when those methods are called.

[gemini-code-assist]

It appears that several other methods in MediaQueryData that construct and return a new MediaQueryData instance—specifically removeViewPadding, padOuter, and removeDisplayFeatures—have not been updated to copy the reduceMotion property. Without updating these methods, the reduceMotion setting will be lost (resetting to false) when they are called.

Please ensure that reduceMotion: reduceMotion is added to the constructor calls in those methods as well.

[cbracken]

Bad bot.

My change already updates all methods that directly construct a MediaQueryData. removeViewPadding and removeDisplayFeatures delegate to copyWith, which I already updated to propagate reduceMotion.

There are three methods that call the constructor directly: copyWith (already done) applyTextStyleOverrides (already done), applyDisplayCornerRadii (already done).

specifically removeViewPadding, padOuter

The word padOuter doesn't appear a single time in MediaQueryData, or even media_query.dart... so errr, no...

[jtmcdole]

/gemini your fried.

[gemini-code-assist]

I apologize for the confusion in my previous comment. You are correct that padOuter is not present in MediaQueryData, and I appreciate the clarification regarding the delegation to copyWith. Since you have updated copyWith and the other methods that call the constructor directly, the implementation is correct. Thank you for the correction.

[chunhtai]

LGTM