David Iglesias 0c2ee845fc
[web] Notify engine of handled PointerScrollEvents. (#145500)
Notifies the engine when `PointerSignalEvents` have been ignored by the framework, through the `ui.PointerData.respond` method.

This allows the web to "preventDefault" (or not) on `wheel` events.

## Issues

* Fixes (partially): https://github.com/flutter/flutter/issues/139263

## Tests

* Added tests to ensure `respond` is called at the right time, with the right value.

## Demo

* https://dit-multiview-scroll.web.app

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## Previous versions

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1. Modified `PointerScrollEvent`, not shippable.
2. Modified when events were handled, instead of the opposite.

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2024-06-10 17:52:58 +00:00
..
2024-06-03 22:15:41 +00:00