This reverts commit ec6da23b.

Reason for revert: Requires infrastructure changes first. Will reland after changes have happened.

Original change's description:
> [flags] Remove some dead Crankshaft flags.
> 
> R=​bmeurer@chromium.org
> BUG=v8:6408
> 
> Change-Id: I34abbcdc2fc47df44938bac0e59f9982c935c657
> Reviewed-on: https://chromium-review.googlesource.com/569963
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#46631}

TBR=mstarzinger@chromium.org,bmeurer@chromium.org

Change-Id: Iee077911ae7d877c6a9d2edb548e3c04345b47ce
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6408
Reviewed-on: https://chromium-review.googlesource.com/570049Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46632}