Revert "Roll R8 and D8 1.4.14 -> 1.5.18"

This reverts commit 9ba66d457f73168b37c4680d5a79e35717f9a838.

Reason for revert: Might be breaking Chromium tree (crbug.com/954179)

Original change's description:
> Roll R8 and D8 1.4.14 -> 1.5.18
>
> Bug: 952640
> Change-Id: I70eb96b3c7ba10df0ecc448316d87a5869a3e3cf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1567895
> Commit-Queue: Sam Maier <smaier@chromium.org>
> Commit-Queue: Andrew Grieve <agrieve@chromium.org>
> Auto-Submit: Sam Maier <smaier@chromium.org>
> Reviewed-by: Andrew Grieve <agrieve@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#650945}

TBR=agrieve@chromium.org,smaier@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

NOTREECHECKS=true

No-Try: true
Bug: 952640, 954179
Change-Id: Ib4143b32944fd6bdfa868abd89099d04040a7e5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1573803
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652154}
2 files changed