* runtime/UString.h: Rolled out the FastAllocBase base class.
It was making UString larger, and therefore JSString larger,
and too big for a garbage collection cell.

This raises the unpleasant possibility that many classes became
larger because we added the FastAllocBase base class. I am
worried about this, and it needs to be investigated.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@53444 268f45cc-cd09-0410-ab3c-d52691b4dbfc