Reland of "Remove ExternalArray, derived types, and element kinds"

Reland of "Remove ExternalArray, derived types, and element kinds"

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

Committed: https://crrev.com/fded08f6949ac3f673f64d3e36be5d03800660e9
Cr-Commit-Position: refs/heads/master@{#29893}

[jochen (gone - plz use gerrit), 2015-07-28 08:24:24]

ptal

2nd patchset contains fix in JSTypedArray::GetBuffer() to not try to externalize
an already neutered external buffer

[Benedikt Meurer, 2015-07-28 09:26:33]

LGTM.

[jochen (gone - plz use gerrit), 2015-07-28 09:26:58]

The CQ bit was checked by jochen@chromium.org

[commit-bot: I haz the power, 2015-07-28 09:27:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1262583002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1262583002/20001

[commit-bot: I haz the power, 2015-07-28 09:29:40]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-28 09:30:08]

Patchset 2 (id:??) landed as
https://crrev.com/fded08f6949ac3f673f64d3e36be5d03800660e9
Cr-Commit-Position: refs/heads/master@{#29893}