Qt Quick Flickable scrolls very slowly when driven from trackpads which produce pixel deltas.

The main reason for this is that the web platform does not support wheel scroll phases. The wasm platform plugin then sends NoPhase for all scroll events, and we end up in the angleDelta path in QQuickFlickable::wheelEvent().

See test case at https://git.qt.io/mosorvig/qt-webassembly-development/-/tree/main/scrolling