[ios]enable the webview non tappable workaround by checking subviews recursively (flutter/engine#57168)

The original workaround ([PR](https://github.com/flutter/engine/pull/56804)) works for the official web view plugin, but it doesn't work for a third party plugin `flutter_inappwebview` ([issue](https://github.com/pichillilorenzo/flutter_inappwebview)). Upon discussion with the author of that plugin, it turns out that their platform view is not a WKWebView, but rather a wrapper of WKWebView. 

This PR performs a DFS search of the view hierarchy, and enable the workaround as long as there's a WKWebView inside. 

TODO: pending sample project:
I am quite positive that it should work, but **I haven't tried it since I don't have a sample project yet**. I have requested a sample project with them so I can verify the solution. 

*List which issues are fixed by this PR. You must list at least one issue.*

 https://github.com/pichillilorenzo/flutter_inappwebview/issues/2415

*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -566,6 +566,18 @@ static BOOL _preparedOnce = NO;
   self.delayingRecognizer.state = UIGestureRecognizerStateFailed;
 }
 
+- (BOOL)containsWebView:(UIView*)view {
+  if ([view isKindOfClass:[WKWebView class]]) {
+    return YES;
+  }
+  for (UIView* subview in view.subviews) {
+    if ([self containsWebView:subview]) {
+      return YES;
+    }
+  }
+  return NO;
+}
+
 - (void)blockGesture {
   switch (_blockingPolicy) {
     case FlutterPlatformViewGestureRecognizersBlockingPolicyEager:
@@ -581,7 +593,7 @@ static BOOL _preparedOnce = NO;
       // FlutterPlatformViewGestureRecognizersBlockingPolicyEager, but we should try it if a similar
       // issue arises for the other policy.
       if (@available(iOS 18.2, *)) {
-        if ([self.embeddedView isKindOfClass:[WKWebView class]]) {
+        if ([self containsWebView:self.embeddedView]) {
           [self removeGestureRecognizer:self.delayingRecognizer];
           [self addGestureRecognizer:self.delayingRecognizer];
         }

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViewsTest.mm

@@ -140,6 +140,46 @@ const float kFloatCompareEpsilon = 0.001;
 
 @end
 
+@interface FlutterPlatformViewsTestMockWrapperWebView : NSObject <FlutterPlatformView>
+@property(nonatomic, strong) UIView* view;
+@property(nonatomic, assign) BOOL viewCreated;
+@end
+
+@implementation FlutterPlatformViewsTestMockWrapperWebView
+- (instancetype)init {
+  if (self = [super init]) {
+    _view = [[UIView alloc] init];
+    [_view addSubview:[[WKWebView alloc] init]];
+    gMockPlatformView = _view;
+    _viewCreated = NO;
+  }
+  return self;
+}
+
+- (UIView*)view {
+  [self checkViewCreatedOnce];
+  return _view;
+}
+
+- (void)checkViewCreatedOnce {
+  if (self.viewCreated) {
+    abort();
+  }
+  self.viewCreated = YES;
+}
+@end
+
+@interface FlutterPlatformViewsTestMockWrapperWebViewFactory : NSObject <FlutterPlatformViewFactory>
+@end
+
+@implementation FlutterPlatformViewsTestMockWrapperWebViewFactory
+- (NSObject<FlutterPlatformView>*)createWithFrame:(CGRect)frame
+                                   viewIdentifier:(int64_t)viewId
+                                        arguments:(id _Nullable)args {
+  return [[FlutterPlatformViewsTestMockWrapperWebView alloc] init];
+}
+@end
+
 namespace flutter {
 namespace {
 class FlutterPlatformViewsTestMockPlatformViewDelegate : public PlatformView::Delegate {
@@ -3153,6 +3193,71 @@ fml::RefPtr<fml::TaskRunner> GetDefaultTaskRunner() {
   }
 }
 
+- (void)
+    testFlutterPlatformViewBlockGestureUnderEagerPolicyShouldRemoveAndAddBackDelayingRecognizerForWrapperWebView {
+  flutter::FlutterPlatformViewsTestMockPlatformViewDelegate mock_delegate;
+
+  flutter::TaskRunners runners(/*label=*/self.name.UTF8String,
+                               /*platform=*/GetDefaultTaskRunner(),
+                               /*raster=*/GetDefaultTaskRunner(),
+                               /*ui=*/GetDefaultTaskRunner(),
+                               /*io=*/GetDefaultTaskRunner());
+  FlutterPlatformViewsController* flutterPlatformViewsController =
+      [[FlutterPlatformViewsController alloc] init];
+  flutterPlatformViewsController.taskRunner = GetDefaultTaskRunner();
+  auto platform_view = std::make_unique<flutter::PlatformViewIOS>(
+      /*delegate=*/mock_delegate,
+      /*rendering_api=*/mock_delegate.settings_.enable_impeller
+          ? flutter::IOSRenderingAPI::kMetal
+          : flutter::IOSRenderingAPI::kSoftware,
+      /*platform_views_controller=*/flutterPlatformViewsController,
+      /*task_runners=*/runners,
+      /*worker_task_runner=*/nil,
+      /*is_gpu_disabled_jsync_switch=*/std::make_shared<fml::SyncSwitch>());
+
+  FlutterPlatformViewsTestMockWrapperWebViewFactory* factory =
+      [[FlutterPlatformViewsTestMockWrapperWebViewFactory alloc] init];
+  [flutterPlatformViewsController
+                   registerViewFactory:factory
+                                withId:@"MockWrapperWebView"
+      gestureRecognizersBlockingPolicy:FlutterPlatformViewGestureRecognizersBlockingPolicyEager];
+  FlutterResult result = ^(id result) {
+  };
+  [flutterPlatformViewsController
+      onMethodCall:[FlutterMethodCall
+                       methodCallWithMethodName:@"create"
+                                      arguments:@{@"id" : @2, @"viewType" : @"MockWrapperWebView"}]
+            result:result];
+
+  XCTAssertNotNil(gMockPlatformView);
+
+  // Find touch inteceptor view
+  UIView* touchInteceptorView = gMockPlatformView;
+  while (touchInteceptorView != nil &&
+         ![touchInteceptorView isKindOfClass:[FlutterTouchInterceptingView class]]) {
+    touchInteceptorView = touchInteceptorView.superview;
+  }
+  XCTAssertNotNil(touchInteceptorView);
+
+  XCTAssert(touchInteceptorView.gestureRecognizers.count == 2);
+  UIGestureRecognizer* delayingRecognizer = touchInteceptorView.gestureRecognizers[0];
+  UIGestureRecognizer* forwardingRecognizer = touchInteceptorView.gestureRecognizers[1];
+
+  XCTAssert([delayingRecognizer isKindOfClass:[FlutterDelayingGestureRecognizer class]]);
+  XCTAssert([forwardingRecognizer isKindOfClass:[ForwardingGestureRecognizer class]]);
+
+  [(FlutterTouchInterceptingView*)touchInteceptorView blockGesture];
+
+  if (@available(iOS 18.2, *)) {
+    // Since we remove and add back delayingRecognizer, it would be reordered to the last.
+    XCTAssertEqual(touchInteceptorView.gestureRecognizers[0], forwardingRecognizer);
+    XCTAssertEqual(touchInteceptorView.gestureRecognizers[1], delayingRecognizer);
+  } else {
+    XCTAssertEqual(touchInteceptorView.gestureRecognizers[0], delayingRecognizer);
+    XCTAssertEqual(touchInteceptorView.gestureRecognizers[1], forwardingRecognizer);
+  }
+}
+
 - (void)
     testFlutterPlatformViewBlockGestureUnderEagerPolicyShouldNotRemoveAndAddBackDelayingRecognizerForNonWebView {
   flutter::FlutterPlatformViewsTestMockPlatformViewDelegate mock_delegate;