Dolt LAST_VALUE uses a ROWS-like implicit frame instead of the default RANGE peer frame

What happened

For legal peer rows, Dolt's implicit LAST_VALUE frame differs from the explicitly written SQL default frame, although the two forms are semantically equivalent.

Environment

Dolt main (commit 92baa5e78afd013b42a62d21b05da0481031e8d0). MySQL version 8.0.43.

How to reproduce

Run the corresponding SQL in a fresh Dolt repository.

CREATE TABLE t(id INT PRIMARY KEY, x INT, v INT);
INSERT INTO t VALUES (1,1,10),(2,1,20),(3,2,30);

SELECT id, x, v,
       LAST_VALUE(v) OVER (ORDER BY x) AS implicit_frame,
       LAST_VALUE(v) OVER (
         ORDER BY x
         RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
       ) AS explicit_equivalent
FROM t
ORDER BY id;

Expected Result

The exact SQL above was run against MySQL 8.0.43. MySQL returned:

1  1  10  20  20
2  1  20  20  20
3  2  30  30  30

With an ordered window and no explicit frame, the SQL default is RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW. Both x=1 peers therefore have the same frame endpoint.

Dolt actual

Dolt returned:

1  1  10  10  20
2  1  20  20  20
3  2  30  30  30

Dolt #11398 concerns an explicit RANGE frame with a NULL key. I guess they are not duplicates.