fix [#660516] by gnat: Restore PHP4 compatibility.

gmap_plugin_style_gmap.inc

@@ -79,13 +79,17 @@ class gmap_plugin_style_gmap extends views_plugin_style {
 
     // Determine fieldname for latitude and longitude fields.
     if ($this->options['datasource'] == 'fields') {
-      $lat_field = $this->view->display_handler->get_handler('field', $this->options['latfield'])->field_alias;
-      $lon_field = $this->view->display_handler->get_handler('field', $this->options['lonfield'])->field_alias;
+      $lat_fied_obj = $this->view->display_handler->get_handler('field', $this->options['latfield']);
+      $lon_field_obj = $this->view->display_handler->get_handler('field', $this->options['lonfield']);
+
+      $lat_field = $lat_fied_obj->field_alias;
+      $lon_field = $lon_field_obj->field_alias;
     }
 
     // Determine fieldname for marker field.
     if ($this->options['markers'] == 'field') {
-      $marker_field = $this->view->display_handler->get_handler('field', $this->options['markerfield'])->field_alias;
+      $marker_field_obj = $this->view->display_handler->get_handler('field', $this->options['markerfield']);
+      $marker_field = $marker_field_obj->field_alias;
     }
 
     $markername = isset($this->options['markertype']) ? $this->options['markertype'] : 'drupal';