Bug 1791245 - More cleanup for the <mfenced> element. r=emilio

The <mfenced> element [1] is not part of MathML Core [2] or MathML AAM
[3] and was removed in bug 1603773. It should be treated as
an unknown MathML element, that is like an `<mrow>`.

This commit performs some follow-up code cleanup:

* Remove a11y mapping, instead map it like an mrow.

* Remove obsolete deprecation message.

* Don't include mfenced in the sanitizer's default element allow list.
  The spec [4] does not mention an explicit list.

* Preference mathml.mfenced_element.disabled was removed, so no need
  to force it when running tests.

* Tweak some code comments.

[1] https://developer.mozilla.org/en-US/docs/Web/MathML/Element/mfenced
[2] https://w3c.github.io/mathml-core/#mathml-elements-and-attributes
[3] https://w3c.github.io/mathml-aam/
[4] https://wicg.github.io/sanitizer-api

Differential Revision: https://phabricator.services.mozilla.com/D157580

accessible/base/MathMLMarkupMap.h

@@ -31,9 +31,7 @@ MARKUPMAP(msqrt_, New_HyperText, roles::MATHML_SQUARE_ROOT)
 
 MARKUPMAP(mroot_, New_HyperText, roles::MATHML_ROOT)
 
-MARKUPMAP(mfenced_, New_HyperText, roles::MATHML_FENCED,
+MARKUPMAP(mfenced_, New_HyperText, roles::MATHML_ROW)
-          AttrFromDOM(close, close), AttrFromDOM(open, open),
-          AttrFromDOM(separators_, separators_))
 
 MARKUPMAP(menclose_, New_HyperText, roles::MATHML_ENCLOSED,
           AttrFromDOM(notation_, notation_))

accessible/base/Role.h

@@ -845,11 +845,6 @@ enum Role {
    */
   MATHML_ROOT = 141,
 
-  /**
-   * A MathML fenced element (mfenced in MathML).
-   */
-  MATHML_FENCED = 142,
-
   /**
    * A MathML enclosed element (menclose in MathML).
    */

accessible/base/RoleMap.h

@@ -1368,8 +1368,6 @@ ROLE(MATHML_OPERATOR,
     // NS_MATHML_OPERATOR_SEPARATOR bits of nsOperatorFlags, but currently they
     // are only available from the MathML layout code. Hence we just fallback
     // to subrole AXMathOperator for now.
-    // XXX bug 1175747 WebKit also creates anonymous operators for <mfenced>
-    // which have subroles AXMathSeparatorOperator and AXMathFenceOperator.
      0,
      IA2_ROLE_UNKNOWN,
      java::SessionAccessibility::CLASSNAME_VIEW,
@@ -1445,16 +1443,6 @@ ROLE(MATHML_ROOT,
      java::SessionAccessibility::CLASSNAME_VIEW,
      eNoNameRule)
 
-ROLE(MATHML_FENCED,
-     "mathml fenced",
-     ATK_ROLE_SECTION,
-     NSAccessibilityGroupRole,
-     @"AXMathFenced",      // XXX bug 1176970 This should be AXMathFence, but doing so without implementing the whole fence interface seems to make VoiceOver crash, so we present it as a row for now.
-     0,
-     IA2_ROLE_UNKNOWN,
-     java::SessionAccessibility::CLASSNAME_VIEW,
-     eNoNameRule)
-
 ROLE(MATHML_ENCLOSED,
      "mathml enclosed",
      ATK_ROLE_SECTION,

accessible/interfaces/nsIAccessibleRole.idl

@@ -838,11 +838,6 @@ interface nsIAccessibleRole : nsISupports
    */
   const unsigned long ROLE_MATHML_ROOT = 141;
 
-  /**
-   * A MathML fenced element (mfenced in MathML).
-   */
-  const unsigned long ROLE_MATHML_FENCED = 142;
-
   /**
    * A MathML enclosed element (menclose in MathML).
    */

accessible/tests/mochitest/elm/test_MathMLSpec.html

@@ -140,11 +140,10 @@
       testElm("mroot", obj);
 
       // ////////////////////////////////////////////////////////////////////////
-      // mfenced
+      // Deprecated mfenced element (treated as an mrow).
 
       obj = {
-        role: ROLE_MATHML_FENCED,
+        role: ROLE_MATHML_ROW,
-        attributes: { open: "]", close: "[", separators: "." },
       };
       testElm("mfenced", obj);
 

dom/base/nsTreeSanitizer.cpp

@@ -749,7 +749,6 @@ const nsStaticAtom* const kElementsMathML[] = {
     nsGkAtoms::median_,               // median
     nsGkAtoms::menclose_,             // menclose
     nsGkAtoms::merror_,               // merror
-    nsGkAtoms::mfenced_,              // mfenced
     nsGkAtoms::mfrac_,                // mfrac
     nsGkAtoms::mglyph_,               // mglyph
     nsGkAtoms::mi_,                   // mi

dom/locales/en-US/chrome/dom/dom.properties

@@ -378,8 +378,6 @@ MathML_DeprecatedMathSizeValueWarning=“small”, “normal” and “big” ar
 # LOCALIZATION NOTE: Do not translate veryverythinmathspace, verythinmathspace,
 # thinmathspace, mediummathspace, thickmathspace, verythickmathspace, veryverythickmathspace and MathML.
 MathML_DeprecatedMathSpaceValueWarning=“veryverythinmathspace”, “verythinmathspace”, “thinmathspace”, “mediummathspace”, “thickmathspace”, “verythickmathspace” and “veryverythickmathspace” are deprecated values for MathML lengths and will be removed at a future date.
-# LOCALIZATION NOTE: Do not translate MathML or mfenced.
-MathML_DeprecatedMfencedElement=MathML element mfenced is deprecated and will be removed at a future date.
 # LOCALIZATION NOTE: Do not translate MathML, background, color, fontfamily, fontsize, fontstyle and fontweight.
 MathML_DeprecatedStyleAttributeWarning=MathML attributes “background”, “color”, “fontfamily”, “fontsize”, “fontstyle” and “fontweight” are deprecated and will be removed at a future date.
 # LOCALIZATION NOTE: Do not translate MathML and STIXGeneral. %S is a documentation URL.

layout/mathml/nsMathMLChar.cpp

@@ -759,8 +759,8 @@ void nsMathMLChar::SetData(nsString& aData) {
 static bool IsSizeOK(nscoord a, nscoord b, uint32_t aHint) {
   // Normal: True if 'a' is around +/-10% of the target 'b' (10% is
   // 1-DelimiterFactor). This often gives a chance to the base size to
-  // win, especially in the context of <mfenced> without tall elements
+  // win, especially in the context of sloppy markups without protective
-  // or in sloppy markups without protective <mrow></mrow>
+  // <mrow></mrow>
   bool isNormal =
       (aHint & NS_STRETCH_NORMAL) &&
       Abs<float>(a - b) < (1.0f - NS_MATHML_DELIMITER_FACTOR) * float(b);

testing/web-platform/meta/mathml/__dir__.ini

@@ -1 +1 @@
-prefs: [mathml.scriptsizemultiplier_attribute.disabled: true, mathml.scriptminsize_attribute.disabled: true, mathml.mathspace_names.disabled: true, mathml.mfenced_element.disabled: true, layout.css.math-style.enabled: true]
+prefs: [mathml.scriptsizemultiplier_attribute.disabled: true, mathml.scriptminsize_attribute.disabled: true, mathml.mathspace_names.disabled: true, layout.css.math-style.enabled: true]