Customize: Improve flow from menu locations to editing a menu.

Adds an Edit button beside the menu location to allow users to switch to the selected menu for further edits.

Props celloexpressions.
Fixes #36795.

git-svn-id: https://develop.svn.wordpress.org/trunk@37901 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/customize/class-wp-customize-nav-menu-location-control.php

@@ -77,6 +77,7 @@ class WP_Customize_Nav_Menu_Location_Control extends WP_Customize_Control {
 				?>
 			</select>
 		</label>
+		<button type="button" class="button edit-menu<?php if ( ! $this->value() ) { echo ' hidden'; } ?>"><?php _e( 'Edit' ); ?></button>
 		<?php
 	}
 }