Add the concept of a V8 extras exports object

Add the concept of a V8 extras exports object

Exposed to the extras as extrasExports (on the builtins object), on
which they can put things that should be accessible from C++. Exposed
to C++ through the V8 API as v8::Context::GetExtrasExportsObject().

Adding a test (in test-api.cc) required adding a simple extra,
test-extra.js, which we build into the standalone builds.

R=yangguo@chromium.org, jochen@chromium.org
BUG=

Committed: https://crrev.com/ad547cea05f3e02c67243b682e933fc53ac763d9
Cr-Commit-Position: refs/heads/master@{#28317}

[domenic, 2015-05-07 13:09:46]

Updated to put the exports object on the builtins object instead of using a
%GetExtrasExportsObject() function.

Can't quite figure out how to exclude the extras-test.js from release builds.
Apparently gyp does not allow changing variable values between release and
debug!? https://plus.sandbox.google.com/116234696297291044849/posts/JtwqPwramW1

[Yang, 2015-05-07 14:03:54]

On 2015/05/07 13:09:46, domenic wrote:
> Updated to put the exports object on the builtins object instead of using a
> %GetExtrasExportsObject() function.
> 
> Can't quite figure out how to exclude the extras-test.js from release builds.
> Apparently gyp does not allow changing variable values between release and
> debug!?
https://plus.sandbox.google.com/116234696297291044849/posts/JtwqPwramW1

LGTM, but please update the CL description.

[jochen (gone - plz use gerrit), 2015-05-07 15:01:36]

lgtm

[domenic, 2015-05-08 10:18:42]

The CQ bit was checked by domenic@chromium.org

[domenic, 2015-05-08 10:18:43]

The patchset sent to the CQ was uploaded after l-g-t-m from jochen@chromium.org,
yangguo@chromium.org
Link to the patchset: https://codereview.chromium.org/1128113006/#ps60001
(title: "Rebase on top of fixed natives change")

[commit-bot: I haz the power, 2015-05-08 10:18:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1128113006/60001

[commit-bot: I haz the power, 2015-05-08 10:21:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-08 10:21:05]

Try jobs failed on following builders:
  v8_mac_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/5645)

[domenic, 2015-05-08 11:24:39]

The CQ bit was checked by domenic@chromium.org

[domenic, 2015-05-08 11:24:40]

The patchset sent to the CQ was uploaded after l-g-t-m from jochen@chromium.org,
yangguo@chromium.org
Link to the patchset: https://codereview.chromium.org/1128113006/#ps80001
(title: "Was mising test-extra.js :(")

[commit-bot: I haz the power, 2015-05-08 11:24:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1128113006/80001

[commit-bot: I haz the power, 2015-05-08 12:06:40]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-05-08 12:06:55]

Patchset 5 (id:??) landed as
https://crrev.com/ad547cea05f3e02c67243b682e933fc53ac763d9
Cr-Commit-Position: refs/heads/master@{#28317}

[Michael Achenbach, 2015-05-08 14:40:27]

This causes gc stress failures:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20s...

[Michael Achenbach, 2015-05-11 08:19:32]

A revert of this CL (patchset #5 id:80001) has been created in
https://codereview.chromium.org/1127313005/ by machenbach@chromium.org.

The reason for reverting is: [Sheriff] Causes gc stress failures:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20s....