This is a reland of ad44c258

Patchset 2 is the original CL
Patchset 3 fixes some misuses of FixedArrayBase::length() and adds some
DCHECKS to flush out any more misuses.
Patchset 4 adds the PPC/S390 port by miladfar@ca.ibm.com.

Original change's description:
> [typedarray] Make JSTypedArray::length authoritative.
>
> This is the first step towards full huge typed array support in V8.
> Before this change, the JSTypedArray::length and the elements backing
> store length (FixedTypedArrayBase::length) were used more or less
> interchangeably to determine the number of elements in a JSTypedArray.
>
> With this change we disentangle these two lengths, and instead make
> JSTypedArray::length authoritative. For on-heap typed arrays, the
> FixedTypedArrayBase::length will remain the number of elements in the
> backing store, but for the off-heap typed arrays, this length will be
> set to 0 (matching the fact that the FixedTypedArrayBase instance does
> not contain any elements itself).
>
> This also unifies the JSTypedArray::set_/length() and length_value()
> methods to only have JSTypedArray::set_/length() which returns/takes
> size_t values. Currently this still requires the values to be in Smi
> range, but later we will extend this to allow arbitrary size_t values
> (in the safe integer range).
>
> Bug: v8:4153, v8:7881
> Change-Id: Iff9089130bb31fa9e08e0cf913e7ab52c3dbf107
> Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
> Doc: http://doc/1Z-wM2qwvAuxH46e9ivtkYvKzzwYZg8ymm0x0wJaomow
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1543729
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#60648}

Bug: v8:4153, v8:7881, v8:9105
Change-Id: Ic38f833071a723642ebc6f82a4012dbc0878ef98
Cq-Include-Trybots: luci.chromium.try:linux-blink-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1594435Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61275}