deps: update v8 to 3.28.73

Reviewed-By: Fedor Indutny <fedor@indutny.com>
PR-URL: https://github.com/joyent/node/pull/8476
deps: apply floating irhydra patch to v8

Reviewed-By: Fedor Indutny <fedor@indutny.com>
PR-URL: https://github.com/joyent/node/pull/8476
deps: fix postmortem-metadata generator in v8

Reviewed-By: Fedor Indutny <fedor@indutny.com>
PR-URL: https://github.com/joyent/node/pull/8476
deps: re-implement debugger-agent

Reviewed-By: Trevor Norris <trevnorris@gmail.com>
PR-URL: https://github.com/joyent/node/pull/8476
cluster: do not signal children in debug mode

Do not send signal to children if they are already in debug mode.
Node.js on Windows does not register signal handler, and thus calling
`process._debugProcess()` will throw an error.

Reviewed-By: Trevor Norris <trevnorris@gmail.com>
PR-URL: https://github.com/joyent/node/pull/8476
src, test: fixup after v8 update

Because of behavior change of some V8 APIs (they mostly became more
    strict), following modules needed to be fixed:

* crypto: duplicate prototype methods are not allowed anymore
* contextify: some TryCatch trickery, the binding was using it
incorrectly
* util: maximum call stack error is now crashing in a different place

Reviewed-By: Trevor Norris <trevnorris@gmail.com>
PR-URL: https://github.com/joyent/node/pull/8476
test: fix debug-signal-cluster after da update

The cluster children are hitting breakpoint at `cluster.onread` and
hanging on a Semaphore wait now. This prevents them from disconnecting
gracefully. Considering that the test is checking different thing, the
cluster children needs to be force killed from the grand parent process.

Reviewed-By: Trevor Norris <trevnorris@gmail.com>
PR-URL: https://github.com/joyent/node/pull/8476