This reverts commit c71fd20c.

Reason for revert: msvc is unhappy (https://build.chromium.org/p/client.v8/builders/V8%20Win64%20-%20msvc/builds/208)

Original change's description:
> [wasm] Data structures for JIT-ing wasm to native memory.
> 
> This CL introduces the structures for JIT-ing wasm on the native heap.
> They are described in detail at go/wasm-on-native-heap-stage-1
> 
> Briefly:
> - WasmCodeManager manages memory for modules and offers an interior
> pointer lookup (i.e. PC -> WasmCode)
> - WasmCode represents code, including reloc info. It holds wasm
> specific data, like function index, and runtime information, like trap
> handler info.
> - NativeModule manages memory for one module.
> 
> Tests cover the allocation and lookup aspects, following that current
> regression tests cover the JITed code. A separate CL will enable JITing
> using the new data structures.
> 
> Bug: v8:6876
> Change-Id: I1731238409001fe97c97eafb7a12fd3922da6a42
> Reviewed-on: https://chromium-review.googlesource.com/767581
> Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#49501}

TBR=bradnelson@chromium.org,ulan@chromium.org,mstarzinger@chromium.org,titzer@chromium.org,mtrofin@chromium.org,mlippautz@chromium.org

Change-Id: Id54deb74782c6f0fd06c61ddcabb727eb7010333
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6876
Reviewed-on: https://chromium-review.googlesource.com/779679Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Commit-Queue: Mircea Trofin <mtrofin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49503}