deps: backport c281c15 from V8's upstream
requested to merge github/fork/misterdjules/add-jstypedarray-length-to-postmortem-metadata into master
Backport c281c15d6dab8370a7805f0717502d260e0ad433 from V8's upstream to allow post-mortem debugging tools to inspect Buffer instances' length.
Original commit message:
Add JSTypedArray's length in post-mortem metadata.
BUG= R=bmeurer@chromium.org
Review URL: https://codereview.chromium.org/1363683002
Cr-Commit-Position: refs/heads/master@{#30873}
/cc @nodejs/post-mortem