You can mark the file with its original type using the same context menu at any time:
Thus, you have a full control of what files should be ignored by IDE’s language support. It may help solve the problems like the one described in WI-322 regarding Yii framework support, about yiilite.php file exclusion.
Of course you may find many other useful scenarios for this feature. Let us know what you think of it and how you use it.
Develop with pleasure!
-JetBrains Web IDE Team