Fix HTML5 key events

Regression from 86f5ac3

platform/javascript/os_javascript.cpp

@@ -468,9 +468,9 @@ void OS_JavaScript::initialize(const VideoMode &p_desired, int p_video_driver, i
 	SET_EM_CALLBACK("#canvas", touchmove, _touchmove_callback)
 	SET_EM_CALLBACK("#canvas", touchend, _touchpress_callback)
 	SET_EM_CALLBACK("#canvas", touchcancel, _touchpress_callback)
-	SET_EM_CALLBACK("#canvas", keydown, _keydown_callback)
-	SET_EM_CALLBACK("#canvas", keypress, _keypress_callback)
-	SET_EM_CALLBACK("#canvas", keyup, _keyup_callback)
+	SET_EM_CALLBACK(NULL, keydown, _keydown_callback)
+	SET_EM_CALLBACK(NULL, keypress, _keypress_callback)
+	SET_EM_CALLBACK(NULL, keyup, _keyup_callback)
 	SET_EM_CALLBACK(NULL, resize, _browser_resize_callback)
 	SET_EM_CALLBACK(NULL, fullscreenchange, _fullscreen_change_callback)
 	SET_EM_CALLBACK_NODATA(gamepadconnected, joy_callback_func)