I discovered this issue while implementing cursor height. With large cursors, it becomes obvious that the cursor is abnormally positioned for empty TextFields, and 'jumps' after a character is entered.

running on macOS:
https://user-images.githubusercontent.com/6655696/103345325-67602680-4a91-11eb-9ae4-91bd1069ada6.mp4

Bottom uses a large cursor, top uses a very large cursor

cc: @justinmc @GaryQian

Related to #64072