Crankshaft flag and opt flag mostly serve the same purpose. Using 
crankshaft to mean use optimizing compiler is a bit confusing.
This cl: https://chromium-review.googlesource.com/c/490206/ fixes 
the tests to use opt instead of crankshaft flag.

One difference between --no-crankshaft and --no-opt would be that 
--no-opt would mean no optimizations at all where as with --no-crankshaft
would mean we can force optimizations using %OptimizeFunctionOnNextCall.

Bug: v8:6325
Change-Id: If17393ac5b6af4ea6e9a98e092f0261c2e0899c5
Reviewed-on: https://chromium-review.googlesource.com/490307Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45298}