Restore enableWebfonts pref and remove uls-enable

This patch restores the enableWebfonts preference, stored inside
the uls-preferences blob. It existed as 'enable-webfonts' in
the past and was removed in
If735a733717596fae03042c5e277bd538bd8501f

Each wiki can be configured to load the fonts by default
using the new global variable $wgULSWebfontsEnabled.
Its default value is true (to load fonts).

This also removes the preference 'uls-enable', recently added in
I71b70d8ee7c3cad7f49b32e5dc494ef4fc1bdb2f

The initialization of ext.uls.webfonts.js is changed as well,
so that minimal webfonts JS library code is loaded,
and the rest is loaded only if a user requests it.

Bug: 60304
Change-Id: I49e812eae32266f165591c75fd67b86ca06b13f0

resources/js/ext.uls.eventlogger.js

@@ -83,6 +83,9 @@
 			mw.hook( 'mw.uls.interface.morelanguages' ).add( $.proxy( this.interfaceMoreLanguages, this ) );
 			mw.hook( 'mw.uls.interface.language.change' ).add( $.proxy( this.interfaceLanguageChange, this ) );
 			mw.hook( 'mw.uls.font.change' ).add( $.proxy( this.fontChange, this ) );
+			mw.hook( 'mw.uls.webfonts.enable' ).add( $.proxy( this.enableWebfonts, this ) );
+			mw.hook( 'mw.uls.webfonts.disable' ).add( $.proxy( this.disableWebfonts, this ) );
+
 			$( 'body' ).on( 'noresults.uls', '.uls-menu .languagefilter',
 				$.proxy( this.noSearchResults, this )
 			);
@@ -208,6 +211,22 @@
 			this.log( logParams );
 		},
 
+		/**
+		 * Log webfonts disabling
+		 * @param {string} context Where the setting was changed.
+		 */
+		disableWebfonts: function ( context ) {
+			this.log( { action: 'webfonts-disable', context: context } );
+		},
+
+		/**
+		 * Log webfonts enabling
+		 * @param {string} context Where the setting was changed.
+		 */
+		enableWebfonts: function ( context ) {
+			this.log( { action: 'webfonts-enable', context: context } );
+		},
+
 		/**
 		 * Log search strings which produce no search results.
 		 * @param {jQuery.event} event The orignal event