deps: update V8 to 4.2.77.21

Picks up the latest patch-release on the V8 4.2 branch.
https://codereview.chromium.org/1156323004

PR-URL: https://github.com/nodejs/io.js/issues/2238
Fixes: https://github.com/nodejs/io.js/issues/2235


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>