I18N: Add context to some theme strings for consistency.

Props ramiy, ocean90.
Fixes #50709.
Built from https://develop.svn.wordpress.org/trunk@48545


git-svn-id: http://core.svn.wordpress.org/trunk@48307 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-theme-upgrader-skin.php

@@ -94,7 +94,7 @@ class Theme_Upgrader_Skin extends WP_Upgrader_Skin {
 					esc_url( $activate_link ),
 					__( 'Activate' ),
 					/* translators: %s: Theme name. */
-					sprintf( __( 'Activate “%s”' ), $name )
+					sprintf( _x( 'Activate “%s”', 'theme' ), $name )
 				);
 			}