IME with input hint along with the cursor can't input

[AmosJin]

Steps to reproduce:

1. use QQ shuangpin IME or IME with input hint along like this: input 't', IME shows 't|[ta]', '|' simulates the cursor position

Expected behaviour: input normally

Observed behaviour: can't input

Workaround: fix the applyChangeToValue inner insert and spliceEnd logic