Remove obsolete Special:Preferences styles after its transformation to OOUI

These removed styles match no elements in the
Special:Preferences page since the OOUI transformation.

Bug: T208923
Change-Id: Iccbdcea5d5f769edfd8640c536e31289da9ee954

skin.json

@@ -95,8 +95,7 @@
 			"+mediawiki.action.view.redirectPage": "skinStyles/mediawiki.action.view.redirectPage.less",
 			"+mediawiki.notification": "skinStyles/mediawiki.notification.less",
 			"+oojs-ui-core.styles": "skinStyles/ooui.less",
-			"mediawiki.special": "skinStyles/mediawiki.special.less",
-			"+mediawiki.special.preferences.styles": "skinStyles/mediawiki.special.preferences.styles.less"
+			"mediawiki.special": "skinStyles/mediawiki.special.less"
 		}
 	},
 	"config": {

skinStyles/mediawiki.special.preferences.styles.less

@@ -1,110 +0,0 @@
-@import 'mediawiki.mixins';
-@import '../variables';
-
-/**
- * The following code is highly modified from monobook. It would be nice if the
- * preftoc id was more human readable like preferences-toc for instance,
- * howerver this would require backporting the other skins.
- */
-.client-js #preftoc {
-	/* Tabs */
-	width: 100%;
-	float: left;
-	clear: both;
-	margin: 0;
-	padding: 0;
-	.background-image('../images/preferences/break.png');
-	background-position: bottom left;
-	background-repeat: no-repeat;
-
-	li {
-		/* Tab */
-		float: left;
-		margin: 0;
-		padding: 0;
-		padding-right: 1px;
-		height: 2.25em;
-		white-space: nowrap;
-		list-style: none none;
-		.background-image('../images/preferences/break.png');
-		background-position: bottom right;
-		background-repeat: no-repeat;
-
-		&:first-child {
-			margin-left: 1px;
-		}
-
-		&.selected {
-			a {
-				.background-image('../images/preferences/fade.png');
-				background-position: bottom;
-				background-repeat: repeat-x;
-				color: @colorText;
-			}
-		}
-	}
-
-	a,
-	a:active {
-		display: inline-block;
-		position: relative;
-		color: @menu-link-color;
-		padding: 0.5em;
-		text-decoration: none;
-		background-image: none;
-		font-size: 0.9em;
-	}
-
-	a:hover,
-	a:focus {
-		text-decoration: underline;
-	}
-}
-
-.client-js #preferences {
-	float: left;
-	width: 100%;
-	margin: 0;
-	margin-top: -2px;
-	clear: both;
-	border: 1px solid @colorGray12;
-	background-color: @colorGray15;
-
-	fieldset {
-		border: 0;
-		border-top: 1px solid @colorGray12;
-	}
-
-	> fieldset {
-		border: 0;
-		padding: 0;
-		margin: 1em;
-
-		> legend {
-			display: none;
-		}
-	}
-
-	legend {
-		color: @colorGray5;
-	}
-
-	td {
-		padding-left: 0.5em;
-		padding-right: 0.5em;
-	}
-
-	div.mw-prefs-buttons {
-		padding: 1em;
-
-		input {
-			margin-right: 0.25em;
-		}
-	}
-}
-
-.htmlform-tip {
-	font-size: x-small;
-	padding: 0.2em 2em;
-	color: @colorGray5;
-}