This is a reland of 71d29f78

Original change's description:
> [nojit] Don't flush the icache in jitless mode
> 
> We don't allocate executable memory in jitless mode hence there's no
> need to flush the icache.
> 
> Bug: v8:7777
> Change-Id: I70a1884e6c9f11405465f5741f2eccd4f7a273fb
> Reviewed-on: https://chromium-review.googlesource.com/c/1488765
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59887}

Bug: v8:7777
Change-Id: Id48455cf4e6d28ad2a0b753580ca51cbe0e983d3
Reviewed-on: https://chromium-review.googlesource.com/c/1491601Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59916}