PlatformView on iOS - duplicate touch events causes assertion failure #27700
Description
Splitting this off from #24207
I believe what's going on is that for accepted gestures when the delaying gesture recognizer rejects, the same touch sequence that was passed to Flutter through the forwarding recognizer is passed again directly to FlutterView.
This fails an assertion resulting in the following error (only in debug mode):
Dart Error: Unhandled exception:
'package:flutter/src/gestures/converter.dart': Failed assertion: line 143 pos 18: '!state.down': is not true.
#0 _AssertionError._doThrowNew (dart:core/runtime/liberrors_patch.dart:40:39)
#1 _AssertionError._throwNew (dart:core/runtime/liberrors_patch.dart:36:5)
#2 PointerEventConverter.expand (package:flutter/src/gestures/converter.dart:143:18)
#3 _SyncIterator.moveNext (dart:core/runtime/libcore_patch.dart:151:12)
#4 ListQueue.addAll (dart:collection/queue.dart:715:25)
#5 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:83:27)
#6 _invoke1 (dart:ui/hooks.dart:165:13)
#7 _dispatchPointerDataPacket (dart:ui/hooks.dart:119:5)