Multisite: Change WP_Network id property to an integer.

For consistency and developer sanity.

Props flixos90.
Fixes #37050.


git-svn-id: https://develop.svn.wordpress.org/trunk@37870 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/multisite/network.php

@@ -87,6 +87,17 @@ class Tests_Multisite_Network extends WP_UnitTestCase {
 		return 3;
 	}
 
+	/**
+	 * @ticket 37050
+	 */
+	function test_wp_network_object_id_property_is_int() {
+		$id = self::factory()->network->create();
+
+		$network = WP_Network::get_instance( $id );
+
+		$this->assertSame( (int) $id, $network->id );
+	}
+
 	/**
 	 * @ticket 22917
 	 */