bug#72573: 29.4; js-mode/JSX: forward-sexp behavior at end of string in JSX fragments

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 11 Aug 2024 16:33:28 +0700
> From: Daan Ro <daanturo@gmail.com>
> 
> Unexpected forward-sexp behavior at the end of strings in JSX fragments
> 
> * Reproduce
> 1. Create file.jsx:
> 
> ```jsx
> 
> function Foo() {
>   // cursor at the end of "cacaca", `forward-sexp-default-function'
>   return (
>     <div>
>       <h1 className="cacaca|">
>         hello world
>         <h2 id="h2-id"></h2>
>       </h1>
>     </div>
>   );
> }
> 
> ```
> 
> 2. Put cursor at the end of "cacaca" (before the closing double quote)
> 3. `C-M-f`/`forward-sexp`
> 
> * Observed: Cursor moves to the beginning of "h2-id".

Here it moves to after the opening quotes of <h1 className="cacaca|">.
This is in Emacs 30.  Looks like some mistake in handling the syntax
of the starting position?

> * Expected: Cursor stays without moving.

Dmitry, could you have a look, please?