The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a9d49a321edf59c960e2109abb66371d59c38572

commit a9d49a321edf59c960e2109abb66371d59c38572
Author: Robert Ma <robertma@chromium.org>
Date: Tue Jan 23 22:00:05 2018

Add a Crash expectation for a custom-elements test

The new version of the test (not imported yet) trips a DCHECK. Since we
currently cannot rebaseline DCHECK failures, we have to mark the test as
Crash manually to unblock wpt-import.

TBR=domenic

No-Try: True
Bug:  805061 
Change-Id: I58b7054eed776a63252610fc4afc7fbaf3a87a35
Reviewed-on: https://chromium-review.googlesource.com/882124
Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531365}
[modify] https://crrev.com/a9d49a321edf59c960e2109abb66371d59c38572/third_party/WebKit/LayoutTests/TestExpectations

Notably this does not fail unless you turn on the experimental web-platform-features. I assume this is part of our half-done customized built-in elements implementation.

STDERR: [1:1:0123/130205.389194:FATAL:V0CustomElementRegistrationContext.cpp(161)] Check failed: !V0CustomElement::IsValidName(element->localName()). 
STDERR: #0 0x00000314d1ec base::debug::StackTrace::StackTrace()
STDERR: #1 0x00000316c2c3 logging::LogMessage::~LogMessage()
STDERR: #2 0x00000559ba76 blink::V0CustomElementRegistrationContext::SetTypeExtension()
STDERR: #3 0x0000051171eb blink::Element::CloneAttributesFromElement()
STDERR: #4 0x000005100923 blink::Element::CloneElementWithoutChildren()
STDERR: #5 0x000004a8613a blink::V8Node::cloneNodeMethodCallback()

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a6c0aa15fad31c353bde8f2b75944cc277d8530c

commit a6c0aa15fad31c353bde8f2b75944cc277d8530c
Author: Kent Tamura <tkent@chromium.org>
Date: Fri Feb 02 06:10:16 2018

custom-elements: Fix a DCHECK failure with external/wpt/custom-elements/upgrading/Node-cloneNode.html.

V0CustomElementRegistrationContext::SetTypeExtension() is not
expected to be called for autonomous custom elements. Element::
AttributeChangedFromParserOrByCloning() should check it.

Bug:  805061 
Change-Id: Ie91256bb6b6b8671d4a6a65374db31394a08d2ea
Reviewed-on: https://chromium-review.googlesource.com/897169
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533972}
[modify] https://crrev.com/a6c0aa15fad31c353bde8f2b75944cc277d8530c/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/a6c0aa15fad31c353bde8f2b75944cc277d8530c/third_party/WebKit/Source/core/dom/Element.cpp