Original issue's description:
> Remove ExternalArray, derived types, and element kinds
>
> BUG=v8:3996
> R=jarin@chromium.org, mvstanton@chromium.org, bmeurer@chromium.org
> LOG=y
>
> Committed: https://crrev.com/607ef7c6009a24ebf195b4cab7b0b436c5afd21c
> Cr-Commit-Position: refs/heads/master@{#29872}

BUG=v8:3996
R=bmeurer@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/1262583002

Cr-Commit-Position: refs/heads/master@{#29893}