Cursor misbehaviour in Safari's <input> controls

[lahickey]

Describe the bug
In Safari (12.1.2), when adding an <input> control with manual two-way binding - by using an 'on:input' handler for instance - changing the contents of the <input> control at any point other than the end of the word causes the cursor to jump to the end of the control.

This does not happen in Chrome (76.0.3809.100) or Firefox (68.0.2). I have not been able to test Edge yet.

To Reproduce
Check out this minimal REPL - https://svelte.dev/repl/db64dcebc4da4ab89100870a9fe7522b?version=3.9.1

In Safari (12.1.2), select the input control in the middle and make any sort of edit. Notice how the cursor jumps to the end of the input control.

Expected behavior
Consistent behaviour across all modern browsers

Severity
Annoying, however I suspect it'll catch more people out as it's such a simple thing to try. I've worked around it by having the variable updated by on:input be different from the one that is used as the initial {value} of the control. I cannot use two-way binding in this case because I'm using the on:input to handle validation.

[Vages]

I've been looking into this for about an hour. No results so far, but there seemed to be a similar problem in Elm for a while: elm/html#174

[Conduitry]

Fixed in 3.17.0.

[dak0rn]

I can still reproduce that issue on 3.18.1 in Safari (macOS and iOS) by moving the assignment into its own component.

https://svelte.dev/repl/0c54225119274537823c4d1077629550?version=3.18.1

[dak0rn]

The problem here seems to be {...$$props}, used to have something similar to Vue's Non-prop attributes/attribute inheritance. Works when it is omitted:

Demonstration:
https://svelte.dev/repl/af09fae984e4408c8b302a27981cf1c2?version=3.18.1