Merged in feature/from-pantheon (pull request #16)

code from pantheon

* code from pantheon

wp/wp-content/plugins/wordpress-importer/compat.php

@@ -0,0 +1,39 @@
+<?php
+/**
+ * Implementation for WordPress functions missing in older WordPress versions.
+ *
+ * @package WordPress
+ * @subpackage Importer
+ */
+
+if ( ! function_exists( 'wp_slash_strings_only' ) ) {
+	/**
+	 * Adds slashes to only string values in an array of values.
+	 *
+	 * Compat for WordPress < 5.3.0.
+	 *
+	 * @since 0.7.0
+	 *
+	 * @param mixed $value Scalar or array of scalars.
+	 * @return mixed Slashes $value
+	 */
+	function wp_slash_strings_only( $value ) {
+		return map_deep( $value, 'addslashes_strings_only' );
+	}
+}
+
+if ( ! function_exists( 'addslashes_strings_only' ) ) {
+	/**
+	 * Adds slashes only if the provided value is a string.
+	 *
+	 * Compat for WordPress < 5.3.0.
+	 *
+	 * @since 0.7.0
+	 *
+	 * @param mixed $value
+	 * @return mixed
+	 */
+	function addslashes_strings_only( $value ) {
+		return is_string( $value ) ? addslashes( $value ) : $value;
+	}
+}