Refactor: Renaming mustache variable `page-isarticle` to `is-article`

Modifies this variable name to use proper hyphen-case and
prioritizes the type of variable rather than it's source.

This prioritization makes sense in Mustache templates because the
variable is a boolean and is used exclusively in if statements,
e.g. {{#is-article}} ... {{/is-article}}

Change-Id: I72e9baf0a979d922b8217aabe8cf0c40699f891b

includes/SkinVector.php

@@ -204,7 +204,7 @@ class SkinVector extends SkinMustache {
 		$commonSkinData = array_merge( $parentData, [
 			'consolidate-user-links' => $this->consolidateUserLinks(),
 
-			'page-isarticle' => (bool)$out->isArticle(),
+			'is-article' => (bool)$out->isArticle(),
 
 			'is-mainpage' => $title->isMainPage(),
 			// Remember that the string '0' is a valid title.

includes/templates/skin-legacy.mustache

@@ -4,7 +4,7 @@
 	Indicator[] array-indicators wiki-defined badges such as "good article",
 		"featured article". An empty array if none are defined.
 	string html-title
-	bool page-isarticle
+	bool is-article
 	string msg-tagline
 	string html-subtitle
 	string html-undelete-link
@@ -33,7 +33,7 @@
 	{{>Indicators}}
 	<h1 id="firstHeading" class="firstHeading" {{{html-user-language-attributes}}}>{{{html-title}}}</h1>
 	<div id="bodyContent" class="mw-body-content">
-		{{#page-isarticle}}<div id="siteSub" class="noprint">{{msg-tagline}}</div>{{/page-isarticle}}
+		{{#is-article}}<div id="siteSub" class="noprint">{{msg-tagline}}</div>{{/is-article}}
 		<div id="contentSub"{{{html-user-language-attributes}}}>{{{html-subtitle}}}</div>
 		<div id="contentSub2">{{{html-undelete-link}}}</div>
 		{{{html-user-message}}}

includes/templates/skin.mustache

@@ -4,7 +4,7 @@
 	Indicator[] array-indicators wiki-defined badges such as "good article",
 		"featured article". An empty array if none are defined.
 	string html-title
-	bool page-isarticle
+	bool is-article
 	string msg-tagline
 	string html-subtitle
 	string html-undelete-link
@@ -64,15 +64,15 @@
 			{{{html-title}}}
 		</h1>
 		{{>Indicators}}
-		{{#page-isarticle}}
+		{{#is-article}}
 			<div id="siteSub" class="noprint">{{msg-tagline}}</div>
-		{{/page-isarticle}}
+		{{/is-article}}
 	</header>
 	{{/is-language-in-header}}
 
 	<div id="bodyContent" class="mw-body-content">
 		{{^is-language-in-header}}
-			{{#page-isarticle}}<div id="siteSub" class="noprint">{{msg-tagline}}</div>{{/page-isarticle}}
+			{{#is-article}}<div id="siteSub" class="noprint">{{msg-tagline}}</div>{{/is-article}}
 		{{/is-language-in-header}}
 		<div id="contentSub"{{{html-user-language-attributes}}}>{{{html-subtitle}}}</div>
 		<div id="contentSub2">{{{html-undelete-link}}}</div>

stories/skin.stories.data.js

@@ -89,7 +89,7 @@ const DATA_INDICATORS = [ {
 
 export const LEGACY_TEMPLATE_DATA = {
 	'html-title': 'Vector 2019',
-	'page-isarticle': true,
+	'is-article': true,
 	'msg-tagline': 'From Wikipedia, the free encyclopedia',
 	'html-user-language-attributes': htmlUserLanguageAttributes,
 	'msg-vector-jumptonavigation': 'Jump to navigation',