Allow for accessing an ArrayBuffer contents without externalizing it

Allow for accessing an ArrayBuffer contents without externalizing it

The embedder has to take appropriate steps to ensure that the
ArrayBuffer doesn't die while it's accessing the pointer, e.g. keep a
Local handle to it around

BUG=none
R=dslomov@chromium.org
LOG=y

Committed: https://crrev.com/ad854ea11e787a673a40b7917a955bee6d7dc253
Cr-Commit-Position: refs/heads/master@{#27942}

[dcarney, 2015-04-20 13:19:56]

dcarney@chromium.org changed reviewers:
+ dcarney@chromium.org

[dcarney, 2015-04-20 13:19:57]

lgtm

https://codereview.chromium.org/1095083002/diff/1/include/v8.h
File include/v8.h (right):

https://codereview.chromium.org/1095083002/diff/1/include/v8.h#newcode3434
include/v8.h:3434: size_t byte_length, bool is_external = true);
no bool args! use enum class outside of class (in v8:: namespace)

[jochen (gone - plz use gerrit), 2015-04-20 13:32:54]

The CQ bit was checked by jochen@chromium.org

[jochen (gone - plz use gerrit), 2015-04-20 13:32:55]

The patchset sent to the CQ was uploaded after l-g-t-m from dcarney@chromium.org
Link to the patchset: https://codereview.chromium.org/1095083002/#ps20001
(title: "updates")

[commit-bot: I haz the power, 2015-04-20 13:33:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1095083002/20001

[commit-bot: I haz the power, 2015-04-20 15:01:59]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-20 15:02:13]

Patchset 2 (id:??) landed as
https://crrev.com/ad854ea11e787a673a40b7917a955bee6d7dc253
Cr-Commit-Position: refs/heads/master@{#27942}