Expose ArrayBufferView::HasBuffer

Expose ArrayBufferView::HasBuffer

This allows the embedder to decide whether it's worthwhile to copy the
contents to avoid materializing a buffer.

BUG=v8:3996
R=dslomov@chromium.org,kbr@chromium.org
LOG=y

Committed: https://crrev.com/ada32ae63651f544801647b7a6fe16f0f6146996
Cr-Commit-Position: refs/heads/master@{#27782}

[Dmitry Lomov (no reviews), 2015-04-13 08:46:09]

lgtm % comment

https://codereview.chromium.org/1084513002/diff/1/include/v8.h
File include/v8.h (right):

https://codereview.chromium.org/1084513002/diff/1/include/v8.h#newcode3515
include/v8.h:3515: * Returns true if ArrayBufferView::Buffer() is a no-op. If it
returns false,
'no-op' is a bad explanation of what 'Buffer' does. 

Better: "returns 'true' if ArrayBufferView's backing ArrayBuffer has already
been alllocated".

[jochen (gone - plz use gerrit), 2015-04-13 11:02:46]

The CQ bit was checked by jochen@chromium.org

[jochen (gone - plz use gerrit), 2015-04-13 11:02:46]

The patchset sent to the CQ was uploaded after l-g-t-m from dslomov@chromium.org
Link to the patchset: https://codereview.chromium.org/1084513002/#ps20001
(title: "updates")

[commit-bot: I haz the power, 2015-04-13 11:02:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1084513002/20001

[commit-bot: I haz the power, 2015-04-13 11:28:07]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-13 11:28:20]

Patchset 2 (id:??) landed as
https://crrev.com/ada32ae63651f544801647b7a6fe16f0f6146996
Cr-Commit-Position: refs/heads/master@{#27782}