build_backtrace called too often on stack unwinding

[bnoordhuis]

function f() { f() }
let count = 0
Error.prepareStackTrace = () => count++
try {
    f()
} catch (e) {
    // ignore
}
print(count) // prints ~157, increases with bigger --stack-size

It's due to the build_backtrace call in JS_CallInternal that's called every time a stack frame is unwound.

Another way of demonstrating the issue:

function f(n) {
    if (--n > 0) f(n)
    else throw Error("unwind")
}
Error.prepareStackTrace = (exc, stk) => print(stk.length)
try {
    f(16)
} catch (e) {
    // ignore
}

Prints:

10
10
10
10
10
10
10
10
10
9
8
7
6
5
4
3
2
1

[bnoordhuis]

Looks to have been introduced in 4c32c53, mea culpa.