- Rewrites the following builtins in Torque:
  WasmThrow
  WasmRethrow
  WasmStackGuard
  WasmStackOverflow
  WasmTraceMemory
  WasmAllocateJSArray
  ThrowWasmTrap* builtins

- Changes return type of LoadContext* functions to NativeContext,
  so we can more easily construct JS objects.

Change-Id: Id034358f9f15e0acc58fd1f493b15d1cfd177a23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2174830
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67621}