Vector uses html-title-heading

The H1 is available with the correct attributes in core now, so
we can use that instead of our own markup. This also means Vector
will benefit from updates to the heading in core such as main page
special handling.

Bug: T297728
Change-Id: I4d10370678fad6455d73994bf340891760543b71

includes/templates/skin-legacy.mustache

@@ -30,7 +30,7 @@
 	<a id="top"></a>
 	<div id="siteNotice">{{{html-site-notice}}}</div>
 	{{>Indicators}}
-	<h1 id="firstHeading" class="firstHeading" {{{html-user-language-attributes}}}>{{{html-title}}}</h1>
+	{{{html-title-heading}}}
 	<div id="bodyContent" class="vector-body">
 		{{#is-article}}<div id="siteSub" class="noprint">{{msg-tagline}}</div>{{/is-article}}
 		<div id="contentSub"{{{html-user-language-attributes}}}>{{{html-subtitle}}}</div>

includes/templates/skin.mustache

@@ -56,7 +56,7 @@
 
 	{{^is-language-in-content}}
 	{{>Indicators}}
-	<h1 id="firstHeading" class="firstHeading" {{{html-user-language-attributes}}}>{{{html-title}}}</h1>
+	{{{html-title-heading}}}
 	{{/is-language-in-content}}
 
 	{{#is-language-in-content}}
@@ -64,7 +64,7 @@
 		{{#is-language-in-content-top}}
 			{{#data-portlets.data-languages}}{{>Menu}}{{/data-portlets.data-languages}}
 		{{/is-language-in-content-top}}
-		<h1 id="firstHeading" class="firstHeading" {{{html-user-language-attributes}}}>{{{html-title}}}</h1>
+		{{{html-title-heading}}}
 		{{>Indicators}}
 		{{#is-article}}
 			<div id="siteSub" class="noprint">{{msg-tagline}}</div>

stories/skin.stories.data.js

@@ -88,6 +88,7 @@ const DATA_INDICATORS = [ {
 
 export const LEGACY_TEMPLATE_DATA = {
 	'html-title': 'Vector 2019',
+	'html-title-heading': '<h1 id="firstHeading" class="firstHeading">Vector 2019</h1>',
 	'is-article': true,
 	'msg-tagline': 'From Wikipedia, the free encyclopedia',
 	'html-user-language-attributes': htmlUserLanguageAttributes,