We can safely lower ToNumeric(x) to ToNumber(x) as long as we can
guarantee that x is any primitive except BigInt (as ToNumeric would
return that unchanged while ToNumber will throw).

Bug: v8:8015
Change-Id: I66573cc204c7c919095ca7598a027fabef7d71a8
Reviewed-on: https://chromium-review.googlesource.com/1199665Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55556}