This mostly pushes code around (from the two specialized public ctors
to the ConfigureFlags method), but does include one behavioral change
in that all builtins/stubs/handlers now disables switch jump tables.

Bug: v8:6666
Change-Id: I801d5bdc7a9c4bcc3bc5eb467a7c049404ffaff0
Reviewed-on: https://chromium-review.googlesource.com/1201785Reviewed-by: Stephan Herhut <herhut@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55652}