This addresses most of the regression in of
Kraken's json-stringify-tinderbox-orig with
31bit Smis: Many object properties become heap
numbers, and printing an integer which is
represented as a double is slower than printing
the integer directly.

Change-Id: I9a14c4da61721b6c3f22e88145acc6a61ed4a419
Bug: v8:8344
Reviewed-on: https://chromium-review.googlesource.com/c/1382741Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58358}