Issue #864: Address failed Travis build by adding 'default' to textdo…

…mains.

In phpcs.xml, add 'default'
And remove the @codingStandardsIgnoreLine tags.

includes/widgets/class-amp-widget-categories.php

@@ -38,8 +38,7 @@ public function modify_select( $dropdown ) {
 	 */
 	public function widget( $args, $instance ) {
 		static $first_dropdown = true;
-		// @codingStandardsIgnoreLine
-		$title                 = ! empty( $instance['title'] ) ? $instance['title'] : __( 'Categories' );
+		$title                 = ! empty( $instance['title'] ) ? $instance['title'] : __( 'Categories', 'default' );
 		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
 		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );
 		$c     = ! empty( $instance['count'] ) ? '1' : '0';
@@ -60,8 +59,7 @@ public function widget( $args, $instance ) {
 			$dropdown_id    = ( $first_dropdown ) ? 'cat' : "{$this->id_base}-dropdown-{$this->number}";
 			$first_dropdown = false;
 			echo '<label class="screen-reader-text" for="' . esc_attr( $dropdown_id ) . '">' . esc_html( $title ) . '</label>';
-			// @codingStandardsIgnoreLine
-			$cat_args['show_option_none'] = __( 'Select Category' );
+			$cat_args['show_option_none'] = __( 'Select Category', 'default' );
 			$cat_args['id']               = $dropdown_id;
 			/**
 			 * Filters the arguments for the Categories widget drop-down.

phpcs.xml

@@ -7,7 +7,7 @@
 
 	<rule ref="WordPress.WP.I18n">
 		<properties>
-			<property name="text_domain" value="amp" />
+			<property name="text_domain" value="amp,default" />
 		</properties>
 	</rule>