This allocates and populates potential exception handler tables before
the underlying {Code} objects is allocated. It essentially makes the
field holding said table immutable after allocation.

R=verwaest@chromium.org
BUG=v8:6792

Change-Id: I52ca374d40e3a72a4de022aca10faead6422db79
Reviewed-on: https://chromium-review.googlesource.com/723299Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48677}