Do not send extra onChangeText even wnen instantianting multiline TextView (facebook#36930)

Summary:
Pull Request resolved: facebook#36930

This diff fixes facebook#36494

Now this code matches its [Fabric counterpart](facebook@7b48899).

There is also one extra check that `_lastStringStateWasUpdatedWith != nil`. With that in place we don't send extra `onChangeText` event when `attributedText` is assigned for the first time on TextView construction.

Changelog: [IOS][Fixed] - Do not send extra onChangeText even wnen instantianting multiline TextView

Reviewed By: sammy-SC

Differential Revision: D45049135

fbshipit-source-id: 62fa281308b9d2e0a807d024f08d8a214bd99b5e

Author: dmytrorykun

Libraries/Text/TextInput/RCTBackedTextInputDelegateAdapter.m

@@ -368,11 +368,10 @@ - (BOOL)textView:(__unused UITextView *)textView shouldChangeTextInRange:(NSRang
 
 - (void)textViewDidChange:(__unused UITextView *)textView
 {
-  if (_ignoreNextTextInputCall && [_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
+  if (_ignoreNextTextInputCall) {
     _ignoreNextTextInputCall = NO;
     return;
   }
-  _lastStringStateWasUpdatedWith = _backedTextInputView.attributedText;
   _textDidChangeIsComing = NO;
   [_backedTextInputView.textInputDelegate textInputDidChange];
 }
@@ -381,10 +380,11 @@ - (void)textViewDidChange:(__unused UITextView *)textView
 
 - (void)textViewDidChangeSelection:(__unused UITextView *)textView
 {
-  if (![_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
+  if (_lastStringStateWasUpdatedWith && ![_lastStringStateWasUpdatedWith isEqual:_backedTextInputView.attributedText]) {
     [self textViewDidChange:_backedTextInputView];
     _ignoreNextTextInputCall = YES;
   }
+  _lastStringStateWasUpdatedWith = _backedTextInputView.attributedText;
   [self textViewProbablyDidChangeSelection];
 }