Store the WasmError longer and only creating the heap Error object (via
ErrorThrower) right before it's being used. This prevents a
DeferredHandleScope and simplifies code a lot.

R=mstarzinger@chromium.org

Bug: v8:8689
Change-Id: Iad98f6facaf1914e4d31edde4221ed8789c1fbfa
Reviewed-on: https://chromium-review.googlesource.com/c/1439116
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59133}