Allow viewport zooming

Bug: T181131
Change-Id: Ifce77610100591222464c576adc0dd0f3f1505ec

Timeless.skin.php

@@ -14,7 +14,10 @@ class SkinTimeless extends SkinTemplate {
 	public function initPage( OutputPage $out ) {
 		parent::initPage( $out );
 
-		$out->addMeta( 'viewport', 'width=device-width, initial-scale=1, maximum-scale=1' );
+		$out->addMeta( 'viewport',
+			'width=device-width, initial-scale=1.0, ' .
+			'user-scalable=yes, minimum-scale=0.25, maximum-scale=5.0'
+		);
 
 		$out->addModuleStyles( [
 			'mediawiki.skinning.content.externallinks',