BREAKING: Better TextInput: contentSize property was removed from <TextInput>.onChange event.

Summary:
`contentSize` was removed from both iOS and Android, tests was updated.
USE `onContentSizeChange` INSTEAD.

Why?
 * It always was a hack;
 * We already have dedicated event for it: `onContentSizeChange`;
 * `onChange` has nothing to do with layout actually;
 * We have to maintain `onChange` handler as fast and simple as possible, this feature complicates it a lot;
 * It was undocumented feature;
 * We already have native auto-expandable <TextInput>, so it illuminates 99% current use cases of this feature.

Reviewed By: mmmulani

Differential Revision: D4680300

fbshipit-source-id: 337836deef0767e5f26350f5a8ce73adb4146a02

Libraries/Text/RCTTextView.m

@@ -489,35 +489,6 @@ static BOOL findMismatch(NSString *first, NSString *second, NSRange *firstRange,
 
   _nativeUpdatesInFlight = NO;
   _nativeEventCount++;
-
-  // TODO: t16435709 This part will be removed soon.
-  if (!self.reactTag || !_onChange) {
-    return;
-  }
-
-  // When the context size increases, iOS updates the contentSize twice; once
-  // with a lower height, then again with the correct height. To prevent a
-  // spurious event from being sent, we track the previous, and only send the
-  // update event if it matches our expectation that greater text length
-  // should result in increased height. This assumption is, of course, not
-  // necessarily true because shorter text might include more linebreaks, but
-  // in practice this works well enough.
-  NSUInteger textLength = textView.text.length;
-  CGFloat contentHeight = textView.contentSize.height;
-  if (textLength >= _previousTextLength) {
-    contentHeight = MAX(contentHeight, _previousContentHeight);
-  }
-  _previousTextLength = textLength;
-  _previousContentHeight = contentHeight;
-  _onChange(@{
-    @"text": self.text,
-    @"contentSize": @{
-      @"height": @(contentHeight),
-      @"width": @(textView.contentSize.width)
-    },
-    @"target": self.reactTag,
-    @"eventCount": @(_nativeEventCount),
-  });
 }
 
 - (void)textViewDidEndEditing:(UITextView *)textView