This CL adds --crankshaft and --no-always-opt flags to the tests that use
assertOptimized() and assertUnoptimized() respectively.

This CL also adds presubmit checks that ensure that tests have the proper
flags set.

BUG=v8:5890

Review-Url: https://codereview.chromium.org/2653753007
Cr-Commit-Position: refs/heads/master@{#42709}