Merge branch '2.8' into 3.4

* 2.8:
  Add note about changed form processing when using PUT requests
  The debug class loader is always loaded by Debug::enable().
  [Intl] Update ICU data to 62.1

Debug.php

@@ -23,10 +23,7 @@ class Debug
     /**
      * Enables the debug tools.
      *
-     * This method registers an error handler and an exception handler.
-     *
-     * If the Symfony ClassLoader component is available, a special
-     * class loader is also registered.
+     * This method registers an error handler, an exception handler and a special class loader.
      *
      * @param int  $errorReportingLevel The level of error reporting you want
      * @param bool $displayErrors       Whether to display errors (for development) or just log them (for production)