When the input to a speculative BigInt operation was an undefined
constant, no necessary type check was inserted by the
RepresentationChanger. This CL fixes this.

Bug: chromium:1077804
Change-Id: I3d4e15b1e018803d56e46c7b23b9d4b03832ba8a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2182455
Commit-Queue: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67610}