The slow test tests SmiLexicographicCompare on a large number of Smi comparisons;
we can disable this test for some debug/noopt builds without losing much coverage.

Bug: v8:7783
Change-Id: Iab40e596604bb957b4d3312073ad85dbac08c6a0
Reviewed-on: https://chromium-review.googlesource.com/1068190
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53333}