Regression(264098@main) HTMLFieldsetElement behavior for :enabled / :…

…disabled CSS selectors is incorrect

https://bugs.webkit.org/show_bug.cgi?id=258078

Reviewed by Tim Nguyen.

264098@main updated HTMLFieldSetElement::isDisabledFormControl() to return false
since a fieldset element can never be disabled per the specification.

This had the side effect of affecting our behavior for :enabled / :disabled CSS
selectors, which relied on this function. However, the behavior of these CSS
selectors shouldn't have changed since they rely on the "actually disabled" state,
not the "disabled" state [1].

There were two issues here, some of our CSS selector logic was relying on
isDisabledFormControl() instead of isActuallyDisabled(). Also, 264098@main
shouldn't have changed the value returned by isActuallyDisabled() for
HTMLFieldsetElements.

This was pointed out at:
- whatwg/html#5886 (comment)

[1] https://html.spec.whatwg.org/multipage/semantics-other.html#selector-enabled
[2] https://html.spec.whatwg.org/multipage/semantics-other.html#selector-disabled
[3] https://html.spec.whatwg.org/multipage/semantics-other.html#concept-element-disabled
[4] https://html.spec.whatwg.org/multipage/form-elements.html#concept-fieldset-disabled

* LayoutTests/imported/w3c/web-platform-tests/html/semantics/selectors/pseudo-classes/disabled.html:
* LayoutTests/imported/w3c/web-platform-tests/html/semantics/selectors/pseudo-classes/enabled.html:
* Source/WebCore/css/SelectorCheckerTestFunctions.h:
(WebCore::matchesEnabledPseudoClass):
* Source/WebCore/html/HTMLElement.h:
* Source/WebCore/html/HTMLFieldSetElement.cpp:
(WebCore::HTMLFieldSetElement::isActuallyDisabled const):
* Source/WebCore/html/HTMLFieldSetElement.h:

Canonical link: https://commits.webkit.org/265166@main

LayoutTests/fast/css/pseudo-indeterminate-radio-buttons-basics-expected.html

@@ -110,7 +110,7 @@
         <input type="radio" name="group12" readonly>
         <span><input type="radio" name="group12" checked readonly class="checked"></span>
     </form>
-    <fieldset disabled>
+    <fieldset disabled class="disabled">
         <input type="radio" class="indeterminate disabled">
         <input type="radio" class="indeterminate disabled">
         <input type="radio" name="group1" class="indeterminate disabled">
@@ -141,7 +141,7 @@
         <span><input type="radio" name="group12" checked readonly class="checked disabled"></span>
     </fieldset>
     <form>
-        <fieldset disabled>
+        <fieldset disabled class="disabled">
             <input type="radio" class="indeterminate disabled">
             <input type="radio" class="indeterminate disabled">
             <input type="radio" name="group1" class="indeterminate disabled">

LayoutTests/imported/w3c/web-platform-tests/html/semantics/selectors/pseudo-classes/disabled.html

@@ -26,6 +26,7 @@
 </select>
 <textarea id=textarea1>textarea1</textarea>
 <textarea disabled id=textarea2>textarea2</textarea>
+<fieldset id=fieldset1></fieldset>
 <fieldset disabled id=fieldset2>
   <legend><input type=checkbox id=club></legend>
   <p><label>Name on card: <input id=clubname required></label></p>
@@ -39,21 +40,21 @@
 <progress disabled></progress>
 
 <script>
-  testSelectorIdsMatch(":disabled", ["button2", "input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should match only disabled elements");
+  testSelectorIdsMatch(":disabled", ["button2", "input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should match only disabled elements");
 
   document.getElementById("button2").removeAttribute("disabled");
-  testSelectorIdsMatch(":disabled", ["input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should not match elements whose disabled attribute has been removed");
+  testSelectorIdsMatch(":disabled", ["input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should not match elements whose disabled attribute has been removed");
 
   document.getElementById("button1").setAttribute("disabled", "disabled");
-  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should also match elements whose disabled attribute has been set");
+  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should also match elements whose disabled attribute has been set");
 
   document.getElementById("button1").setAttribute("disabled", "disabled");
-  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should also match elements whose disabled attribute has been set twice");
+  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should also match elements whose disabled attribute has been set twice");
 
   document.getElementById("input2").setAttribute("type", "submit"); // change input type to submit
-  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should also match disabled elements whose type has changed");
+  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should also match disabled elements whose type has changed");
 
   var input = document.createElement("input");
   input.setAttribute("disabled", "disabled");
-  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "clubname", "clubnum"], "':disabled' should not match elements not in the document");
+  testSelectorIdsMatch(":disabled", ["button1", "input2", "select2", "optgroup2", "option2", "textarea2", "fieldset2", "clubname", "clubnum"], "':disabled' should not match elements not in the document");
 </script>

LayoutTests/imported/w3c/web-platform-tests/html/semantics/selectors/pseudo-classes/enabled.html

@@ -36,6 +36,7 @@
  </menu>
 </form>
 <fieldset id=fieldset1></fieldset>
+<fieldset disabled id=fieldset2></fieldset>
 
 <script>
   testSelectorIdsMatch(":enabled", ["button1", "input1", "select1", "optgroup1", "option1", "textarea1", "submitbutton", "fieldset1"], "':enabled' elements that are not disabled");

Source/WebCore/css/SelectorCheckerTestFunctions.h

@@ -96,7 +96,7 @@ ALWAYS_INLINE bool matchesDisabledPseudoClass(const Element& element)
 // https://html.spec.whatwg.org/multipage/scripting.html#selector-enabled
 ALWAYS_INLINE bool matchesEnabledPseudoClass(const Element& element)
 {
-    return is<HTMLElement>(element) && downcast<HTMLElement>(element).canBeActuallyDisabled() && !element.isDisabledFormControl();
+    return is<HTMLElement>(element) && downcast<HTMLElement>(element).canBeActuallyDisabled() && !downcast<HTMLElement>(element).isActuallyDisabled();
 }
 
 // https://dom.spec.whatwg.org/#concept-element-defined

Source/WebCore/html/HTMLElement.h

@@ -122,7 +122,7 @@ class HTMLElement : public StyledElement {
 
     // Only some element types can be disabled: https://html.spec.whatwg.org/multipage/scripting.html#concept-element-disabled
     bool canBeActuallyDisabled() const;
-    bool isActuallyDisabled() const;
+    virtual bool isActuallyDisabled() const;
 
 #if ENABLE(AUTOCAPITALIZE)
     WEBCORE_EXPORT virtual AutocapitalizeType autocapitalizeType() const;

Source/WebCore/html/HTMLFieldSetElement.cpp

@@ -73,6 +73,13 @@ bool HTMLFieldSetElement::isDisabledFormControl() const
     return HTMLFormControlElement::isDisabledFormControl();
 }
 
+// https://html.spec.whatwg.org/#concept-element-disabled
+// https://html.spec.whatwg.org/#concept-fieldset-disabled
+bool HTMLFieldSetElement::isActuallyDisabled() const
+{
+    return HTMLFormControlElement::isDisabledFormControl();
+}
+
 static void updateFromControlElementsAncestorDisabledStateUnder(HTMLElement& startNode, bool isDisabled)
 {
     auto range = inclusiveDescendantsOfType<Element>(startNode);

Source/WebCore/html/HTMLFieldSetElement.h

@@ -45,6 +45,7 @@ class HTMLFieldSetElement final : public HTMLFormControlElement {
     ~HTMLFieldSetElement();
 
     bool isDisabledFormControl() const final;
+    bool isActuallyDisabled() const final;
     bool isEnumeratable() const final { return true; }
     bool supportsFocus() const final;
     RenderPtr<RenderElement> createElementRenderer(RenderStyle&&, const RenderTreePosition&) final;