VE-1521 Cross-browser compatible widget for clearing text input

https://wikia-inc.atlassian.net/browse/VE-1521
Ad: "Hmm maybe it should throw an exception if that option is passed, or do you think there is a use case for a clearable textarea?"

I'm not aware of already existing use case for it, there might be one in the future but who knows.

Either comment about it in the constructor or throwing exception sounds good to me.