Remove menclose in cancel rendering

Chrome and similar browsers do not support the
menclose tag. This change introduces a css polyfill
suggested in

w3c/mathml-core#245 (comment)

but keeps the mencose rendering since FF does not
support the polyfill

https://bugzilla.mozilla.org/show_bug.cgi?id=1929800

Bug: T376829
Change-Id: I860e2f2f9bf9eef8eeba35b0999ec50175fdfc4b

modules/ext.math.css

@@ -79,3 +79,31 @@ mtd.mwe-math-matrix-left {
 mtd.mwe-math-matrix-right {
 	border-right: 0.06em solid;
 }
+
+/* see https://github.com/w3c/mathml-core/issues/245#issuecomment-2410676518 */
+menclose.menclose {
+	position: relative;
+	padding: 0.5ex 0;
+}
+
+mrow.menclose-updiagonalstrike {
+	display: inline-block;
+	position: absolute;
+	left: 0.5px;
+	bottom: 0;
+	width: 100%;
+	height: 100%;
+	background-color: currentcolor;
+	clip-path: polygon( 0.05em 100%, 0 calc( 100% - 0.05em ), calc( 100% - 0.05em ) 0, 100% 0.05em );
+}
+
+mrow.menclose-downdiagonalstrike {
+	display: inline-block;
+	position: absolute;
+	left: 0.5px;
+	bottom: 0;
+	width: 100%;
+	height: 100%;
+	background-color: currentcolor;
+	clip-path: polygon( 0 0, 0.05em 0, 100% 100%, calc( 100% - 0.05em ) 100% );
+}

src/WikiTexVC/MMLmappings/BaseParsing.php

@@ -159,10 +159,14 @@ public static function boldsymbol( $node, $passedArgs, $operatorContent, $name,
 		return $mrow->encapsulateRaw( $node->getArg()->renderMML( $passedArgs ) );
 	}
 
-	public static function cancel( $node, $passedArgs, $operatorContent, $name, $notation = null, $smth2 = null ) {
-		$mrow = new MMLmrow();
-		$menclose = new MMLmenclose( "", [ "notation" => $notation ] );
-		return $mrow->encapsulateRaw( $menclose->encapsulateRaw( $node->getArg()->renderMML() ) );
+	public static function cancel( Fun1 $node, $passedArgs, $operatorContent, $name, $notation = '' ): string {
+		$outer = new MMLmenclose( '', [ 'notation' => $notation, 'class' => 'menclose' ] );
+		$bars = '';
+		foreach ( explode( ' ', $notation ) as $element ) {
+			$bars .= ( new MMLmrow( '', [ 'class' => 'menclose-' . $element ] ) )->getEmpty();
+		}
+
+		return $outer->encapsulateRaw( $node->getArg()->renderMML() . $bars );
 	}
 
 	public static function cancelTo( $node, $passedArgs, $operatorContent, $name, $notation = null ) {

tests/phpunit/unit/WikiTexVC/MMLmappings/BaseParsingTest.php

@@ -67,7 +67,9 @@ public function testCancel() {
 			( new Literal( 'a' ) )
 		);
 		$result = BaseParsing::cancel( $node, [], null, 'cancel', 'something' );
-		$this->assertStringContainsString( '<menclose notation="something"><mi>a</mi></menclose>',
+		$this->assertStringContainsString( '<mi>a</mi><mrow class="menclose-something"/>',
+			$result );
+		$this->assertStringContainsString( '<menclose notation="something" class="menclose">',
 			$result );
 	}