src: use global SealHandleScope
src: use global SealHandleScope

Helps to find Handle leaks in Debug mode.

PR-URL: https://github.com/iojs/io.js/pull/1395
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node