Summary:
We have the wrong calculation of placeholder size currently, leads `contentSize` or some things inaccuracy.
[iOS] [Fixed] - Fixed wrong placeholder size calculation in multiline text input mode
Pull Request resolved: https://github.com/facebook/react-native/pull/23682
Differential Revision: D14255932
Pulled By: cpojer
fbshipit-source-id: a1f40e90fc2c848579694965da8316fae9e5c4c5