Chinese IME sogou，cause crash by editing text before a inline-element

[OldDream]

Description
Chinese IME sogou，cause crash by editing text before a inline-element.
select -> input by sogou IME -> crash

Recording

Sandbox

This bug can be reproduce with official online demo.
https://www.slatejs.org/examples/mentions

Steps
To reproduce the behavior:

1. select all characters befor @R2-D2
2. start input with sogou IME
3. then the bug show up.
4. See error in console:
   Uncaught Error: Cannot resolve a Slate point from DOM point: [object Text],2 at Object.toSlatePoint ([example]-5e4f16b701ecada0.js:1:99830) at Object.toSlateRange ([example]-5e4f16b701ecada0.js:1:100498) at HTMLDocument.<anonymous> ([example]-5e4f16b701ecada0.js:1:117948) at g (674-c731382ea76bd727.js:1:1377655) at b (674-c731382ea76bd727.js:1:1377711) at HTMLDocument.z (674-c731382ea76bd727.js:1:1378030) at g (674-c731382ea76bd727.js:1:1377655) at S (674-c731382ea76bd727.js:1:1377930) at w (674-c731382ea76bd727.js:1:1377820)

Context
The official demo can work smooth with Microsoft's chinese IME, so I'm not sure if this is a bug. But sogou IME is widely used in china. So it would be very helpful if we can fix this.

[washanhanzi]

#5762