Reviewed by Geoffrey Garen.

        Make it harder to use HandleSlot incorrectly
        https://bugs.webkit.org/show_bug.cgi?id=59205

        Just add a little type fudging to make it harder to
        incorrectly assign through a HandleSlot.

        * API/JSCallbackObjectFunctions.h:
        (JSC::::init):
        * JavaScriptCore.exp:
        * heap/Handle.h:
        (JSC::HandleBase::operator!):
        (JSC::HandleBase::operator UnspecifiedBoolType*):
        (JSC::HandleTypes::getFromSlot):
        * heap/HandleHeap.cpp:
        (JSC::HandleHeap::markStrongHandles):
        (JSC::HandleHeap::markWeakHandles):
        (JSC::HandleHeap::finalizeWeakHandles):
        (JSC::HandleHeap::writeBarrier):
        (JSC::HandleHeap::protectedGlobalObjectCount):
        (JSC::HandleHeap::isValidWeakNode):
        * heap/HandleHeap.h:
        (JSC::HandleHeap::copyWeak):
        (JSC::HandleHeap::makeWeak):
        (JSC::HandleHeap::Node::slot):
        * heap/HandleStack.cpp:
        (JSC::HandleStack::mark):
        (JSC::HandleStack::grow):
        * heap/HandleStack.h:
        (JSC::HandleStack::zapTo):
        (JSC::HandleStack::push):
        * heap/Heap.cpp:
        (JSC::HandleHeap::protectedObjectTypeCounts):
        * heap/Local.h:
        (JSC::::set):
        * heap/Strong.h:
        (JSC::Strong::set):
        * heap/Weak.h:
        (JSC::Weak::set):
        * runtime/StructureTransitionTable.h:
        (JSC::StructureTransitionTable::singleTransition):
        (JSC::StructureTransitionTable::setSingleTransition):
        * runtime/WeakGCMap.h:
        (JSC::WeakGCMap::add):
        (JSC::WeakGCMap::set):
        * runtime/WriteBarrier.h:
        (JSC::OpaqueJSValue::toJSValue):
        (JSC::OpaqueJSValue::toJSValueRef):
        (JSC::OpaqueJSValue::fromJSValue):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@84650 268f45cc-cd09-0410-ab3c-d52691b4dbfc