[Safari macOS Sierra] Korean character composition not work correctly

[silverprize]

[Describe the issue]

Steps for Reproduction

1. Visit quilljs.com
2. Set caret position at the beginning of the line
3. Set Korean ime
4. Do typing 가나다라

Expected behavior:
가나다라

Actual behavior:
ㄱㅏ나다라

Platforms:
macOS sierra 10.12.4(16E195)
Safari 10.1(12603.1.30.0.34)

Version:
1.2.4

[mave99a]

Same for Chinese. Looks like it always take the first character entered.

Expected behavior:
测试

Actual behavior:
c测试

c was entered，because 'c' is the first char entered for Chinese Pin Yin IME.

[kidlj]

Same problem like @mave99a above, with Windows 10/ Chrome 60/ Microsoft Pin Yin IME

[warwr1ck]

it happens in ie11 too, window 10

[geekftz]

so how to fix it ? I try to upadte version to 1.3.6, but the question still exist.