Back out "[react-native][PR] [iOS] Fixes selection of single line text input"

Summary:
Original commit changeset: f149721d6b4d (D15238379)

This commit was causing the following crash: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'An instance 0x7fb3453eda00 of class RCTUITextField was deallocated while key value observers were still registered with it.

FB: See also P64445585 T44107377 T44169319

Reviewed By: mmmulani

Differential Revision: D15323255

fbshipit-source-id: 037c34ae387d912c5ea03eaa364b8c60367df357

Author: JoshuaGross

Libraries/Text/TextInput/RCTBackedTextInputDelegateAdapter.m

@@ -28,27 +28,15 @@ - (instancetype)initWithTextField:(UITextField<RCTBackedTextInputViewProtocol> *
 
     [_backedTextInputView addTarget:self action:@selector(textFieldDidChange) forControlEvents:UIControlEventEditingChanged];
     [_backedTextInputView addTarget:self action:@selector(textFieldDidEndEditingOnExit) forControlEvents:UIControlEventEditingDidEndOnExit];
-    [_backedTextInputView addObserver:self forKeyPath:@"selectedTextRange" options:NSKeyValueObservingOptionNew context:NULL];
   }
 
   return self;
 }
 
-- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
-{
-  // UITextField doesn't have a delegate like UITextView to get notified on selection. Use KVO to observe changes.
-  if ([keyPath isEqualToString:@"selectedTextRange"]) {
-    [self textFieldProbablyDidChangeSelection];
-  } else {
-    [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
-  }
-}
-
 - (void)dealloc
 {
   [_backedTextInputView removeTarget:self action:nil forControlEvents:UIControlEventEditingChanged];
   [_backedTextInputView removeTarget:self action:nil forControlEvents:UIControlEventEditingDidEndOnExit];
-  [_backedTextInputView removeObserver:self forKeyPath:@"selectedTextRange"];
 }
 
 #pragma mark - UITextFieldDelegate