Add a scoped context object for synchronous CE creation

Add a scoped context object for synchronous CE creation

In synchronous custom element creation
(e.g. document.createElement('my-element')),
context object is not passed down to the constructor.

CustomElementCreationScope manages a scoped context
in LocalDOMWindow.

BUG=640465

[kochi, 2016-08-25 06:32:02]

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

[commit-bot: I haz the power, 2016-08-25 06:32:21]

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

[kochi, 2016-08-25 06:42:21]

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

[commit-bot: I haz the power, 2016-08-25 06:42:37]

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

[kochi, 2016-08-25 07:40:59]

Description was changed from

==========
Tentative: Scoped context


BUG=640465
==========

to

==========
Add a scoped context object for synchronous CE creation

In synchronous custom element creation
(e.g. document.createElement('my-element')),
context object is not passed down to the constructor.

CustomElementCreationScope manages a scoped context
in LocalDOMWindow.

BUG=640465
==========

[kochi, 2016-08-25 07:41:11]

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

[commit-bot: I haz the power, 2016-08-25 07:41:38]

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, 2016-08-25 07:45:09]

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

[commit-bot: I haz the power, 2016-08-25 07:45:10]

Dry run: Try jobs failed on following builders:
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[kochi, 2016-08-25 07:59:33]

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

[kochi, 2016-08-25 07:59:41]

Patchset #3 (id:40001) has been deleted

[commit-bot: I haz the power, 2016-08-25 08:00:03]

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

[kojii, 2016-08-25 08:14:43]

We should probably have CustomElementCreationScope in
CustomElement::createCustomElementSync so that callers do not have to take care
of it. Doing so will probably make this CL as small as the other candidate.

The other one shares more code between create and upgrade, so I have mild
preference to it, but I might be biased by it's my CL? WDYT?

[commit-bot: I haz the power, 2016-08-25 09:30:35]

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

[commit-bot: I haz the power, 2016-08-25 09:30:36]

Dry run: This issue passed the CQ dry run.

[kochi, 2016-08-25 09:32:24]

On 2016/08/25 08:14:43, kojii wrote:
> We should probably have CustomElementCreationScope in
> CustomElement::createCustomElementSync so that callers do not have to take
care
> of it. Doing so will probably make this CL as small as the other candidate.
> 
> The other one shares more code between create and upgrade, so I have mild
> preference to it, but I might be biased by it's my CL? WDYT?

Yeah, your change seems more streamlined and even unifies two
paths (upgrade/create), so let's go for yours.