Missing postmortem constant

[targos]

AssertionError [ERR_ASSERTION]: Missing constants: v8dbg_context_idx_closure
    at Object.<anonymous> (/home/mzasso/git/nodejs/canary/test/parallel/test-postmortem-metadata.js:48:8)

[cjihrig]

I'll look into it.

[targos]

Fixed in #60