Approved intent: https://groups.google.com/a/chromium.org/forum/#!topic/Blink-dev/1WO1qyjG3GQ

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/58c06a5f1b87ec32101c95e17f52189fed28158a

commit 58c06a5f1b87ec32101c95e17f52189fed28158a
Author: tkent <tkent@chromium.org>
Date: Fri Dec 02 16:05:14 2016

FIELDSET element: |elements| IDL attribute should return an HTMLCollection, not HTMLFormControlsCollection.

Specification: https://html.spec.whatwg.org/multipage/forms.html#dom-fieldset-elements
Intent: https://groups.google.com/a/chromium.org/forum/#!topic/Blink-dev/1WO1qyjG3GQ

* HTMLFormControlsCollection:
 Remove <fieldset> support

* HTMLCollection:
  Add support for FormControls collection rooted at <fieldset>.
  Note that some functions are used by HTMLFormControlsCollection too.

* Update tests
  Make sure RadioNodeList isn't used.
  Unlike HTMLFormControlsCollection, fieldset.elements doesn't have an exception
  for <input type=image> [1]. So elements.length increased.

[1] https://html.spec.whatwg.org/multipage/forms.html#dom-form-elements

BUG= 665291 

Review-Url: https://codereview.chromium.org/2548453003
Cr-Commit-Position: refs/heads/master@{#435946}

[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/LayoutTests/fast/forms/fieldset/fieldset-elements-expected.txt
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/LayoutTests/fast/forms/fieldset/fieldset-elements.html
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/LayoutTests/fast/forms/fieldset/fieldset-form-collection-radionode-list-expected.txt
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/LayoutTests/fast/forms/fieldset/fieldset-form-collection-radionode-list.html
[delete] https://crrev.com/6f5774cd1b3e4d956437fd50762d5cdf3d0221ff/third_party/WebKit/LayoutTests/imported/wpt/html/semantics/forms/the-fieldset-element/HTMLFieldSetElement-expected.txt
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/frame/UseCounter.h
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/html/HTMLCollection.cpp
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/html/HTMLFieldSetElement.cpp
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/html/HTMLFieldSetElement.h
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/html/HTMLFieldSetElement.idl
[modify] https://crrev.com/58c06a5f1b87ec32101c95e17f52189fed28158a/third_party/WebKit/Source/core/html/HTMLFormControlsCollection.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/932af91289f138471791a1dc30a2660ac719b55b

commit 932af91289f138471791a1dc30a2660ac719b55b
Author: tkent <tkent@chromium.org>
Date: Tue Dec 06 08:30:54 2016

Cleanup of blink::HTMLFieldSetElement

m_listedElements and related code are unnecessary now. |elements| HTML collection
is identical to m_listedElements.  m_listedElements was necessary because
m_listedElements was a source of HTMLFormControlsCollection though vanilla
HTMLCollection doesn't need such source.

This CL has no behavior changes.

BUG= 665291 

Review-Url: https://codereview.chromium.org/2550993002
Cr-Commit-Position: refs/heads/master@{#436544}

[modify] https://crrev.com/932af91289f138471791a1dc30a2660ac719b55b/third_party/WebKit/Source/core/html/HTMLFieldSetElement.cpp
[modify] https://crrev.com/932af91289f138471791a1dc30a2660ac719b55b/third_party/WebKit/Source/core/html/HTMLFieldSetElement.h