Reviewed by Oliver.
        
        - enable polymorphic inline caching of properties of primitives
        
        1.012x speedup on SunSpider.

        We create special structure IDs for JSString and
        JSNumberCell. Unlike normal structure IDs, these cannot hold the
        true prototype. Due to JS autoboxing semantics, the prototype used
        when looking up string or number properties depends on the lexical
        global object of the call site, not the creation site. Thus we
        enable StructureIDs to handle this quirk for primitives.
        
        Everything else should be straightforward.
        
        * VM/CTI.cpp:
        (JSC::CTI::privateCompileGetByIdProto):
        (JSC::CTI::privateCompileGetByIdChain):
        * VM/CTI.h:
        (JSC::CTI::compileGetByIdProto):
        (JSC::CTI::compileGetByIdChain):
        * VM/JSPropertyNameIterator.h:
        (JSC::JSPropertyNameIterator::JSPropertyNameIterator):
        * VM/Machine.cpp:
        (JSC::Machine::Machine):
        (JSC::cachePrototypeChain):
        (JSC::Machine::tryCachePutByID):
        (JSC::Machine::tryCacheGetByID):
        (JSC::Machine::privateExecute):
        (JSC::Machine::tryCTICachePutByID):
        (JSC::Machine::tryCTICacheGetByID):
        * kjs/GetterSetter.h:
        (JSC::GetterSetter::GetterSetter):
        * kjs/JSCell.h:
        * kjs/JSGlobalData.cpp:
        (JSC::JSGlobalData::JSGlobalData):
        * kjs/JSGlobalData.h:
        * kjs/JSGlobalObject.h:
        (JSC::StructureID::prototypeForLookup):
        * kjs/JSNumberCell.h:
        (JSC::JSNumberCell::JSNumberCell):
        (JSC::jsNumberCell):
        * kjs/JSObject.h:
        (JSC::JSObject::prototype):
        * kjs/JSString.cpp:
        (JSC::jsString):
        (JSC::jsSubstring):
        (JSC::jsOwnedString):
        * kjs/JSString.h:
        (JSC::JSString::JSString):
        (JSC::JSString::):
        (JSC::jsSingleCharacterString):
        (JSC::jsSingleCharacterSubstring):
        (JSC::jsNontrivialString):
        * kjs/SmallStrings.cpp:
        (JSC::SmallStrings::createEmptyString):
        (JSC::SmallStrings::createSingleCharacterString):
        * kjs/StructureID.cpp:
        (JSC::StructureID::StructureID):
        (JSC::StructureID::addPropertyTransition):
        (JSC::StructureID::getterSetterTransition):
        (JSC::StructureIDChain::StructureIDChain):
        * kjs/StructureID.h:
        (JSC::StructureID::create):
        (JSC::StructureID::storedPrototype):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@36316 268f45cc-cd09-0410-ab3c-d52691b4dbfc