Move call of Sanitizer::decodeCharReferences from Skin to Parser

Supporting HTML entities in Wikitext is part of the parser not of the
skin.

Change-Id: Ib30ff08f4f4ce585f31211aa24b719783f06456e

includes/parser/ParserOutput.php

@@ -259,7 +259,7 @@ class ParserOutput extends CacheTime {
 					global $wgOut, $wgLang;
 					$editsectionPage = Title::newFromText( htmlspecialchars_decode( $m[1] ) );
 					$editsectionSection = htmlspecialchars_decode( $m[2] );
-					$editsectionContent = isset( $m[4] ) ? $m[3] : null;
+					$editsectionContent = isset( $m[4] ) ? Sanitizer::decodeCharReferences( $m[3] ) : null;
 
 					if ( !is_object( $editsectionPage ) ) {
 						throw new MWException( "Bad parser output text." );

includes/skins/Skin.php

@@ -1578,8 +1578,6 @@ abstract class Skin extends ContextSource {
 
 		$attribs = [];
 		if ( !is_null( $tooltip ) ) {
-			# T27462: undo double-escaping.
-			$tooltip = Sanitizer::decodeCharReferences( $tooltip );
 			$attribs['title'] = wfMessage( 'editsectionhint' )->rawParams( $tooltip )
 				->inLanguage( $lang )->text();
 		}