fieldset:disabled fieldset > legend:first-child input should be disabled

fieldset:disabled fieldset > legend:first-child input should be disabled
https://bugs.webkit.org/show_bug.cgi?id=129077

Reviewed by Antti Koivisto.

Source/WebCore:

Similar to r164403. When a fieldset inside a disabled fieldset, input elements inside
the inner fieldset's first legend element child should be disabled.

Test: fast/forms/fieldset/fieldset-disabled-2.html

* html/HTMLFieldSetElement.cpp:
(WebCore::HTMLFieldSetElement::legend): Fixed the bug where it was returning the first
legend element descendent. It should be the first legend element _child_.
* html/HTMLFormControlElement.cpp:
(WebCore::HTMLFormControlElement::updateAncestorDisabledState): Fixed the algorithm
to look for any ancestor fieldset that has been disabled instead of the first fieldset
ancestor and checking its disabledness.

LayoutTests:

Added a test case.o

* fast/forms/fieldset/fieldset-disabled-2-expected.txt:
* fast/forms/fieldset/fieldset-disabled-2.html:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@164407 268f45cc-cd09-0410-ab3c-d52691b4dbfc