The same thing goes for create-element-inside-template.html

But this time we want to make sure that it is "undefined" not "failed".

I think there is no problem with state-failed-create.html

I will take a look at other 2 files.

Patch up at https://codereview.chromium.org/2313573002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/44d4690c35729c1cfa0f6d78df1de3e5effdf871

commit 44d4690c35729c1cfa0f6d78df1de3e5effdf871
Author: davaajav <davaajav@google.com>
Date: Wed Sep 07 09:21:57 2016

CustomelElements: add prototype check for "failed" elements

There 2 possible ways to set an element`s state to "failed":
1. create the element for the token
   https://html.spec.whatwg.org/multipage/syntax.html#create-an-element-for-the-token
2. upgrade the element
   https://html.spec.whatwg.org/#concept-upgrade-an-element
According to the spec, "failed" element should implement HTMLUnknownElement
only while it is being created for the token, not while it is being upgraded.

Added prototype sanity check when an element is created inside a template.

BUG= 643509 

Review-Url: https://codereview.chromium.org/2313573002
Cr-Commit-Position: refs/heads/master@{#416886}

[modify] https://crrev.com/44d4690c35729c1cfa0f6d78df1de3e5effdf871/third_party/WebKit/LayoutTests/custom-elements/spec/create-element-inside-template.html
[modify] https://crrev.com/44d4690c35729c1cfa0f6d78df1de3e5effdf871/third_party/WebKit/LayoutTests/custom-elements/spec/state-failed-create.html
[add] https://crrev.com/44d4690c35729c1cfa0f6d78df1de3e5effdf871/third_party/WebKit/LayoutTests/custom-elements/spec/state-failed-upgrade-expected.txt
[modify] https://crrev.com/44d4690c35729c1cfa0f6d78df1de3e5effdf871/third_party/WebKit/LayoutTests/custom-elements/spec/state-failed-upgrade.html

Is there anything left to do here?

I think we can close it.