Merge commit '7621e2f8dec938cf48181c8b10afc9b01f444e68' into beta

submodules/AsyncDisplayKit/Source/ASResponderChainEnumerator.mm

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+//
+//  ASResponderChainEnumerator.mm
+//  Texture
+//
+//  Copyright (c) Facebook, Inc. and its affiliates.  All rights reserved.
+//  Changes after 4/13/2017 are: Copyright (c) Pinterest, Inc.  All rights reserved.
+//  Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
+//
+
+#import "ASResponderChainEnumerator.h"
+#import <AsyncDisplayKit/ASAssert.h>
+
+@implementation ASResponderChainEnumerator {
+  UIResponder *_currentResponder;
+}
+
+- (instancetype)initWithResponder:(UIResponder *)responder
+{
+  ASDisplayNodeAssertMainThread();
+  if (self = [super init]) {
+    _currentResponder = responder;
+  }
+  return self;
+}
+
+#pragma mark - NSEnumerator
+
+- (id)nextObject
+{
+  ASDisplayNodeAssertMainThread();
+  id result = [_currentResponder nextResponder];
+  _currentResponder = result;
+  return result;
+}
+
+@end
+
+@implementation UIResponder (ASResponderChainEnumerator)
+
+- (NSEnumerator *)asdk_responderChainEnumerator
+{
+  return [[ASResponderChainEnumerator alloc] initWithResponder:self];
+}
+
+@end