`this` is undefined inside a do…while body in non-class functions (breaks node-forge rsa_sign)

[proggeramlug]

Found by the package matrix re-run (#11723): node-forge/rsa_sign throws TypeError: … (reading 'data'). Reproduces 3/3 at 9e29f59 and on origin/main 9e05951.

Inside a do…while body, this is undefined in any non-class function. A plain while loop works, and so does a class method.

const o = { d: 7, f(n) { let r = 0; do { r += this.d; n--; } while (n > 0); return r; } };
console.log(o.f(1)); // node: 7; perry: throws TypeError

[proggeramlug]

Hint for whoever picks this up: a fix attempt that was stopped part-way traced it to two separate statement walkers that don't handle do…while bodies the same way (likely the this/captures analysis after #11637 made this a body parameter). The planned fix was to replace both walkers with one exhaustive helper, so no statement kind can be missed. Please also check for/for-in/for-of/labeled loops/continue paths, and arguments/new.target inside do-while. Acceptance: the repro matches Node, and node-forge/rsa_sign passes (scripts/package_bench.py, benchmarks/packages).