Reviewed by Oliver Hunt.

Rename Rope::m_ropeLength to m_fiberCount, to be more descriptive.
Rename Rope::m_stringLength to simply m_length (since this is the
more conventional name for the length of a string).  Move append
behaviour out into a new RopeBuilder class, so that Rope no longer
needs any knowledge of the JSString or UString implementation.

Make Rope no longer be nested within JSString.
(Rope now no-longer need reside within JSString.h, but leaving
the change of moving this out to a different header as a separate
change from these renames).

* JavaScriptCore.exp:
* jit/JITOpcodes.cpp:
(JSC::JIT::privateCompileCTIMachineTrampolines):
* runtime/JSString.cpp:
(JSC::Rope::destructNonRecursive):
(JSC::Rope::~Rope):
(JSC::JSString::resolveRope):
(JSC::JSString::toBoolean):
(JSC::JSString::getStringPropertyDescriptor):
* runtime/JSString.h:
(JSC::Rope::Fiber::Fiber):
(JSC::Rope::Fiber::deref):
(JSC::Rope::Fiber::ref):
(JSC::Rope::Fiber::refAndGetLength):
(JSC::Rope::Fiber::isRope):
(JSC::Rope::Fiber::rope):
(JSC::Rope::Fiber::isString):
(JSC::Rope::Fiber::string):
(JSC::Rope::Fiber::nonFiber):
(JSC::Rope::tryCreateUninitialized):
(JSC::Rope::append):
(JSC::Rope::fiberCount):
(JSC::Rope::length):
(JSC::Rope::fibers):
(JSC::Rope::Rope):
(JSC::Rope::operator new):
(JSC::):
(JSC::RopeBuilder::JSString):
(JSC::RopeBuilder::~JSString):
(JSC::RopeBuilder::length):
(JSC::RopeBuilder::canGetIndex):
(JSC::RopeBuilder::appendStringInConstruct):
(JSC::RopeBuilder::appendValueInConstructAndIncrementLength):
(JSC::RopeBuilder::isRope):
(JSC::RopeBuilder::fiberCount):
(JSC::JSString::getStringPropertySlot):
* runtime/Operations.h:
(JSC::jsString):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@54804 268f45cc-cd09-0410-ab3c-d52691b4dbfc