Add @@species/better subclassing support to Promises

Add @@species/better subclassing support to Promises

This patch makes Promise.prototype.then use @@species as specified
in ES2015. The fix is hoped for by certain users, such as legacy
core.js versions which encounter an unhandled Promise reject (complete
with an ugly console message) when Promise subclassing is supported
in a mostly correct way, and we do error checking on Promise
constructors, but @@species is not supported.

BUG=chromium:575314, v8:4633
LOG=Y
R=adamk

Committed: https://crrev.com/569145019d8af8330a4702ace5bd93a9e51077f2
Cr-Commit-Position: refs/heads/master@{#33225}

[Dan Ehrenberg, 2016-01-12 01:59:34]

PTAL. This patch depends on https://codereview.chromium.org/1574903004

[adamk, 2016-01-12 02:18:37]

lgtm

[Dan Ehrenberg, 2016-01-12 06:09:04]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2016-01-12 06:09:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1577223002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1577223002/1

[commit-bot: I haz the power, 2016-01-12 06:33:00]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-01-12 06:33:20]

Description was changed from

==========
Add @@species/better subclassing support to Promises

This patch makes Promise.prototype.then use @@species as specified
in ES2015. The fix is hoped for by certain users, such as legacy
core.js versions which encounter an unhandled Promise reject (complete
with an ugly console message) when Promise subclassing is supported
in a mostly correct way, and we do error checking on Promise
constructors, but @@species is not supported.

BUG=chromium:575314,v8:4633
LOG=Y
R=adamk
==========

to

==========
Add @@species/better subclassing support to Promises

This patch makes Promise.prototype.then use @@species as specified
in ES2015. The fix is hoped for by certain users, such as legacy
core.js versions which encounter an unhandled Promise reject (complete
with an ugly console message) when Promise subclassing is supported
in a mostly correct way, and we do error checking on Promise
constructors, but @@species is not supported.

BUG=chromium:575314,v8:4633
LOG=Y
R=adamk

Committed: https://crrev.com/569145019d8af8330a4702ace5bd93a9e51077f2
Cr-Commit-Position: refs/heads/master@{#33225}
==========

[commit-bot: I haz the power, 2016-01-12 06:33:20]

Patchset 1 (id:??) landed as
https://crrev.com/569145019d8af8330a4702ace5bd93a9e51077f2
Cr-Commit-Position: refs/heads/master@{#33225}