This reverts commit d4c8393c.

Reason for revert: Breaks ARM hardware:
https://build.chromium.org/p/client.v8.ports/builders/V8%20Arm%20-%20debug/builds/5268

Original change's description:
> [wasm] JIT using WasmCodeManager
> 
> This is the first step towards wasm code sharing. This CL moves wasm
> code generation outside the JavaScript GC heap using the previously -
> introduced WasmCodeManager (all this, behind the --wasm-jit-to-native
> flag).
> 
> See design document: go/wasm-on-native-heap-stage-1
> 
> This CL doesn't change other wasm architectural invariants. We still
> have per-Isolate wasm code generation, and per-wasm module instance
> code specialization.
> 
> Bug:v8:6876
> 
> Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
> Change-Id: I1e08cecad75f93fb081545c31228a4568be276d3
> Reviewed-on: https://chromium-review.googlesource.com/674086
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Reviewed-by: Eric Holk <eholk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49689}

TBR=bradnelson@chromium.org,titzer@chromium.org,mtrofin@chromium.org,eholk@chromium.org

Change-Id: I89af1ea5decd841bc12cd2ceaf74d32bc4433885
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6876
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/794690Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49691}