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.ime.js

@@ -150,8 +150,11 @@
 			e.stopPropagation();
 		} );
 
-		// apply fonts to this
-		imeselector.$menu.webfonts();
+		// If the webfonts are loaded, apply webfonts to the selector
+		if ( $.fn.webfonts ) {
+			imeselector.$menu.webfonts();
+		}
+
 		return $( '<div>' )
 			.addClass( 'uls-ime-menu-settings-item' )
 			.append( $disableInputToolsLink, $moreSettingsLink );