Index: src/wp-admin/plugin-editor.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/wp-admin/plugin-editor.php	(revision 36196)
+++ src/wp-admin/plugin-editor.php	(revision )
@@ -164,7 +164,7 @@
 		}
 	}
 
-	$content = esc_textarea( $content );
+	$content = esc_plugineditor( $content );
 	?>
 <?php if (isset($_GET['a'])) : ?>
  <div id="message" class="updated notice is-dismissible"><p><?php _e('File edited successfully.') ?></p></div>
Index: src/wp-includes/formatting.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- src/wp-includes/formatting.php	(revision 36196)
+++ src/wp-includes/formatting.php	(revision )
@@ -3589,6 +3589,27 @@
 }
 
 /**
+ * Escaping for plugin editor textarea.
+ *
+ * @since 4.5.0
+ *
+ * @param string $text
+ * @return string
+ */
+function esc_plugin_source( $text ) {
+	$safe_text = htmlspecialchars( $text, ENT_QUOTES );
+	/**
+	 * Filter a string cleaned and escaped for output in a textarea element.
+	 *
+	 * @since 3.1.0
+	 *
+	 * @param string $safe_text The text after it has been escaped.
+	 * @param string $text      The text prior to being escaped.
+	 */
+	return apply_filters( 'esc_plugin_source', $safe_text, $text );
+}
+
+/**
  * Escape an HTML tag name.
  *
  * @since 2.5.0