Fix mozilla expectations after regexp change.

TBR=ulan@chromium.org

Review URL: https://codereview.chromium.org/749963002

Cr-Commit-Position: refs/heads/master@{#25458}
Remove deprecated ShouldSelfOptimize machinery.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/582683002

Cr-Commit-Position: refs/heads/master@{#25459}
ARM64: skip flaky mozilla/ecma/Date/15.9.5.26-1 until it is fixed.

BUG=v8:3716
LOG=N

Review URL: https://codereview.chromium.org/746983002

Cr-Commit-Position: refs/heads/master@{#25460}