Inline the promise constructor when we have one argument and target
matches new_target.

This is not complete, and is sitting behind an experimental flag for
now. We need to fix deoptimization by providing proper frame states.

Create a unittest class for JSCallReducer - just assert whether there
was a change or not, rather than specify the exact graph that should be
produced.

Bug: v8:7253
Change-Id: Ib6886a8feb2799f47cd647853cabcf12a189bc25
Reviewed-on: https://chromium-review.googlesource.com/919282
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51389}