Factor out gin::IsolateHolder's constructor

Factor out gin::IsolateHolder's constructor.

Before this CL, gin::IsolateHolder was created in the constructor
of V8PerIsolateData, and it is less useful to customized usages.
This CL moves the creation of IsolateHolder out of V8PerIsolateData
and make it more flexible.



BUG=617892

[peria, 2017-02-20 07:37:20]

Patchset #1 (id:1) has been deleted

[peria, 2017-02-20 07:41:34]

The CQ bit was checked by peria@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-20 07:41:48]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[peria, 2017-02-20 07:48:12]

Description was changed from

==========
Factor out gin::IsolateHolder's constructor

BUG=
==========

to

==========
Factor out gin::IsolateHolder's constructor.

Before this CL, gin::IsolateHolder was created in the constructor
of V8PerIsolateData, and it is less useful to customized usages.
This CL moves the creation of IsolateHolder out of V8PerIsolateData
and make it more flexible.


BUG=617892
==========

[commit-bot: I haz the power, 2017-02-20 08:40:27]

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

[commit-bot: I haz the power, 2017-02-20 08:40:28]

Dry run: Try jobs failed on following builders:
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[peria, 2017-02-20 08:48:18]

Description was changed from

==========
Factor out gin::IsolateHolder's constructor.

Before this CL, gin::IsolateHolder was created in the constructor
of V8PerIsolateData, and it is less useful to customized usages.
This CL moves the creation of IsolateHolder out of V8PerIsolateData
and make it more flexible.


BUG=617892
==========

to

==========
Factor out gin::IsolateHolder's constructor.

Before this CL, gin::IsolateHolder was created in the constructor
of V8PerIsolateData, and it is less useful to customized usages.
This CL moves the creation of IsolateHolder out of V8PerIsolateData
and make it more flexible.



BUG=617892
==========

[peria, 2017-02-20 08:59:49]

The CQ bit was checked by peria@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-20 09:00:05]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-20 11:59:23]

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

[commit-bot: I haz the power, 2017-02-20 11:59:23]

Dry run: This issue passed the CQ dry run.