REST API: JS client - QUnit tests for custom namespace route discovery.

Add QUnit tests for the parsing of custom namespace routes. Add a custom schema fixture based on the `wp-js-widgets` plugin. Test that the client can parse the widget namespace in the schema and correctly construct the expected group of models and collections. Also includes a small unrelated QUnit fix to ensure nav-menu test passes when it is loaded without its tests executing as well as a small jshint fix, adding a missing semicolon since [40107].

Props jnylen0.
Fixes #39561.

Built from https://develop.svn.wordpress.org/trunk@40109


git-svn-id: http://core.svn.wordpress.org/trunk@40046 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/theme.js

@@ -1928,7 +1928,7 @@ themes.RunInstaller = {
 				// Open the theme preview.
 				self.view.collection.once( 'query:success', function() {
 					$( 'div[data-slug="' + slug + '"]' ).trigger( 'click' );
-				})
+				});
 
 			}
 		});

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40108';
+$wp_version = '4.8-alpha-40109';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.