Use this in the PromiseThen operation to skip the (expensive) lookup in
the SpeciesConstructor operation. This yields in a nice 3-5% improvement
on the bluebird and wikipedia benchmarks, and paves the way for inlining
certain Promise operations into TurboFan optimized code later.

On the micro-benchmark mentioned in the bug (from the findings doc), we
reduce the overall execution time by 25%, which makes sense given that
Promise.prototype.then spends a significant portion of it's time just
figuring out the appropriate constructor.

Bug: v8:7253, v8:7349
Change-Id: Ia1577b59d1b7e4b8dbda83e2186583edab76695a
Reviewed-on: https://chromium-review.googlesource.com/880681Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50794}