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## Summary Set up the experiment to migrate event dispatching in the React Native renderer to be based on the native EventTarget API. Behind the `enableNativeEventTargetEventDispatching` flag, events are dispatched through `dispatchTrustedEvent` instead of the legacy plugin system. Regular event handler props are NOT registered via addEventListener at commit time. Instead, a hook on EventTarget (`EVENT_TARGET_GET_DECLARATIVE_LISTENER_KEY`) extracts handlers from `canonical.currentProps` at dispatch time, shifting cost from every render to only when events fire. The hook is overridden in ReactNativeElement to look up the prop name via a reverse mapping from event names (built lazily from the view config registry). Responder events bypass EventTarget entirely. `negotiateResponder` walks the fiber tree directly (capture then bubble phase), calling handlers from `canonical.currentProps` and checking return values inline. Lifecycle events (`responderGrant`, `responderMove`, etc.) call handlers directly from props and inspect return values — `onResponderGrant` returning `true` blocks native responder, `onResponderTerminationRequest` returning `false` refuses termination. This eliminates all commit-time cost for responder events (no wrappers, no addEventListener, no `responderWrappers` on canonical). ## How did you test this change? Flow Tested e2e in RN using Fantom tests (that will land after this).