async_wrap,src: wrap promises directly

Promises do not have any internal fields by default. V8 recently added
the capability of configuring the number of internal fields on promises.
This change adds an internal field to promises allowing promises to be
wrapped directly by the PromiseWrap object. In addition to cleaner code
this avoids an extra object allocation per promise and speeds up promise
creation with async_hooks enabled by ~2x.

PR-URL: https://github.com/nodejs/node/pull/13242
Ref: https://github.com/nodejs/node/pull/13224


Reviewed-By: Andreas Madsen <amwebdk@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>