Remove UntypedPtrAndBitfield from UStringImpl (akin to PtrAndFlags).

Reviewed by Oliver Hunt.

This break the OS X Leaks tool.  Instead, free up some more bits from the refCount.

* runtime/UStringImpl.cpp:
(JSC::UStringImpl::sharedBuffer):
(JSC::UStringImpl::~UStringImpl):
* runtime/UStringImpl.h:
(JSC::UStringImpl::cost):
(JSC::UStringImpl::checkConsistency):
(JSC::UStringImpl::UStringImpl):
(JSC::UStringImpl::bufferOwnerString):
(JSC::UStringImpl::):
* wtf/StringHashFunctions.h:
(WTF::stringHash):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@53392 268f45cc-cd09-0410-ab3c-d52691b4dbfc