ToC: Handle anchors with % in plaintext

TODO: Remove the fallback to {{anchor}} when all old parser cache expired.

Bug: T315222
Change-Id: I1da089cfef83131cda26859e3346cd2d840b3839

includes/templates/TableOfContents__line.mustache

@@ -1,6 +1,6 @@
 <li id="toc-{{anchor}}"
 	class="sidebar-toc-list-item sidebar-toc-level-{{toclevel}}{{#is-top-level-section}}{{^vector-is-collapse-sections-enabled}} sidebar-toc-list-item-expanded{{/vector-is-collapse-sections-enabled}}{{/is-top-level-section}}">
-	<a class="sidebar-toc-link" href="#{{anchor}}">
+	<a class="sidebar-toc-link" href="#{{linkAnchor}}{{^linkAnchor}}{{anchor}}{{/linkAnchor}}">
 		<div class="sidebar-toc-text">
 		<span class="sidebar-toc-numb">{{number}}</span>{{{line}}}</div>
 	</a>

tests/phpunit/integration/SkinVectorTest.php

@@ -64,6 +64,7 @@ class SkinVectorTest extends MediaWikiIntegrationTestCase {
 					'fromtitle' => 'Test',
 					'byteoffset' => 231,
 					'anchor' => 'A',
+					'linkAnchor' => 'A',
 					'array-sections' =>	[],
 					'is-top-level-section' => true,
 					'is-parent-section' => false,
@@ -77,6 +78,7 @@ class SkinVectorTest extends MediaWikiIntegrationTestCase {
 					'fromtitle' => 'Test',
 					'byteoffset' => 245,
 					'anchor' => 'B',
+					'linkAnchor' => 'B',
 					'array-sections' =>	[],
 					'is-top-level-section' => true,
 					'is-parent-section' => false,
@@ -95,6 +97,7 @@ class SkinVectorTest extends MediaWikiIntegrationTestCase {
 					'fromtitle' => 'Test',
 					'byteoffset' => 231,
 					'anchor' => 'A',
+					'linkAnchor' => 'A',
 					'array-sections' => [
 						'toclevel' => 2,
 						'level' => '4',
@@ -104,6 +107,7 @@ class SkinVectorTest extends MediaWikiIntegrationTestCase {
 						'fromtitle' => 'Test',
 						'byteoffset' => 245,
 						'anchor' => 'A1',
+						'linkAnchor' => 'A1',
 						'array-sections' => [],
 						'is-top-level-section' => false,
 						'is-parent-section' => false,