REST API: Fix multi-type schemas with integer fields.

In [48306] support for multi-typed schemas was improved to first detect the data type of the value before applying further validation. The `integer` data type was detected using the new `rest_is_integer` function. This function used logic, however, that assumed that the value had already passed an `is_numeric` check. This meant that if `integer` and `string` were both acceptable types, the value would always be considered an `integer` causing the later accurate type validation to fail.

This commit fixes the `rest_is_integer` logic to include an `is_numeric` check.

Props rtagliento.
Fixes #51146.

Built from https://develop.svn.wordpress.org/trunk@48881


git-svn-id: http://core.svn.wordpress.org/trunk@48643 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api.php

@@ -1315,7 +1315,7 @@ function rest_is_boolean( $maybe_bool ) {
  * @return bool True if an integer, otherwise false.
  */
 function rest_is_integer( $maybe_integer ) {
-	return round( floatval( $maybe_integer ) ) === floatval( $maybe_integer );
+	return is_numeric( $maybe_integer ) && round( floatval( $maybe_integer ) ) === floatval( $maybe_integer );
 }
 
 /**

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.6-alpha-48880';
+$wp_version = '5.6-alpha-48881';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.