This CL changes the call-site of SmiLexicographicCompare to a fast
c call instead of a runtime call. The runtime function is not deleted
as it is still used in InnerArraySort.

The test is also moved from mjsunit to cctest, to make removal of the
runtime function easier in the future.

R=cbruni@chromium.org, jgruber@chromium.org

Bug: v8:7382
Change-Id: Ie961eeb094c13018e9ec28b68f7c444d7f889036
Reviewed-on: https://chromium-review.googlesource.com/1201587
Commit-Queue: Simon Zünd <szuend@google.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55642}