Await safety not yet fixed in swing-store/src/snapStore.js for runSteps loop

[erights]

agoric-sdk/packages/xsnap/src/replay.js

Line 213 in 293f88e

for (const step of steps) {

The triage currently at #6219 would fix it, with the explanation and code

    // Changed from `for of` to `for await of` to make awaits within
    // loop body safer. A `for await of` will correctly process a synchronous
    // iterator, but it still unconditionally separates the iterations
    // with turn boundaries.
    for await (const step of steps) {

Most of #6219 consists of commentary or cosmetic code changes, and so can be postponed until after PS0. But this is a safety fix. Whether we should cherry pick it, to get it in before PS0 depends on what the consequences are of not fixing it.

Assigning myself since I have the fix done in #6219 and would do the cherry picking if we decide to do that.

Git blame shows @dckc as the one who should probably investigate this, so I'm assigning to them as well. Feel free to reassign as appropriate of course.

Also assigning @dtribble since he commented on this one and suggested that we not fix it, or at least not fix it this way because of performance concerns.

[erights]

With the simpler await safety rule, this issue is obsolete. Closing.