I think a simpler fix is to use the `originalLength` property where appropriate for places that use the range returned from `getCurrentRange()`. `getCurrentRange()` is only called in 2 places"

1. `_handleHostDocumentChange` - this is called when user edits doc when editor is open, so I think this should not be changed. 

2. `_handleTimingFunctionChange` - line 172 (I think) should be changed to:

```
    ch: range.start.ch + (timingFunctionString.originalLength || timingFunctionString.length)
```

I tried this out and it seems to work.