Bug Description

When a GestureArenaMember calls resolve(GestureDisposition.accepted) while the arena is open, it becomes the eagerWinner via state.eagerWinner ??= member. If that same member subsequently calls resolve(GestureDisposition.rejected) while the arena is still open, _resolve removes the member from state.members but never clears state.eagerWinner. This leaves a dangling reference to an already-rejected-and-removed member.

When the arena later closes, _tryToResolveArena checks state.eagerWinner != null and delegates to _resolveInFavorOf with the stale member. This causes:

• The stale member to receive acceptGesture despite having already been rejected (assertion failure in debug mode via _CombiningGestureArenaMember._close)
• All remaining legitimate members to be incorrectly rejected

Steps to Reproduce

1. Add 3 members (A, B, C) to a gesture arena
2. Member A calls resolve(accepted) → becomes eagerWinner
3. Member A calls resolve(rejected) → removed from members, but eagerWinner still points to A
4. Close the arena → stale eagerWinner (A) incorrectly wins, B and C are rejected

Expected Behavior

When a rejected member was the eagerWinner, eagerWinner should be cleared so the arena resolves normally among remaining members.

Fix

PR: #187008

Clear state.eagerWinner in the rejected case when the rejected member matches the current eagerWinner:

case GestureDisposition.rejected:
  if (state.eagerWinner == member) {
    state.eagerWinner = null;
  }
  state.members.remove(member);