This reverts commit 4b86fea5.

Reason for revert: Fails on linux shared: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20shared/31045

Original change's description:
> [typedarray] Move external/data pointer to JSTypedArray.
> 
> As the next step in supporting huge typed arrays in V8, this moves the
> external/data pointer from the FixedTypedArrayBase backing store to the
> JSTypedArray instance itself, and replaces the special backing stores
> with a plain ByteArray (removing all the code for the FixedTypedArrayBase
> class hierarchy). By doing so, we can drastically simplify the system
> around typed arrays.
> 
> Note: Several places in the code base used to check the instance type
> of the elements backing store of a JSTypedArray instead of checking the
> elements kind on the JSTypedArray map directly. Those had to be fixed,
> since the backing store is now always a ByteArray.
> 
> Drive-by-fix: Move all the typed elements access related code into the
> elements.cc file to properly encapsulate the accesses.
> 
> Doc: http://doc/1Z-wM2qwvAuxH46e9ivtkYvKzzwYZg8ymm0x0wJaomow
> Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
> Change-Id: I8cc06b190c53e34155000b4560f5f3ef40621646
> Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627535
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Peter Marshall <petermarshall@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61855}

TBR=ulan@chromium.org,yangguo@chromium.org,titzer@chromium.org,sigurds@chromium.org,petermarshall@chromium.org,bmeurer@chromium.org,szuend@chromium.org

Change-Id: I0bc1f935de6063acf75a0f4bb8c0ba67428603fd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:951196, chromium:965583, v8:4153, v8:7881, v8:9183
Cq-Include-Trybots: luci.chromium.try:linux-rel, win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1631427Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61856}