Reviewed by Maciej Stachowiak.

        Some Handle<T> cleanup
        https://bugs.webkit.org/show_bug.cgi?id=58109

        * bytecode/SamplingTool.h: Sorted alphabetically because that's the
        WebKit style. Added a Global.h #include that was previously missing
        but harmless.

        * collector/handles/Global.h:
        (JSC::Global::Global): Added a null constructor. No need for a special
        tag, and the tag is incompatible with some data structures.
        
        (JSC::Global::isHashTableDeletedValue):
        (JSC::Global::~Global):
        (JSC::Global::set):
        (JSC::Global::operator=):
        (JSC::Global::clear):
        (JSC::Global::hashTableDeletedValue): Reordered constructors to be near
        each other.

        (JSC::Global::setWithWriteBarrier): Renamed internalSet to
        setWithWriteBarrier for clarity, and funneled more code into using set
        and setWithWriteBarrier to reduce duplication.

        * collector/handles/Handle.h:
        (JSC::HandleBase::operator!):
        (JSC::HandleBase::HandleBase): Removed isEmpty(), since we already have
        boolean and ! operators.

        (JSC::HandleBase::slot):
        (JSC::HandleBase::setSlot):
        (JSC::Handle::Handle): Added general support for null Handles. This was
        previously outlawed by ASSERTs, but our code has grown to support and
        rely on null Handles.
        
        * collector/handles/HandleHeap.cpp:
        (JSC::HandleHeap::markWeakHandles):
        (JSC::HandleHeap::finalizeWeakHandles):
        (JSC::HandleHeap::isValidWeakNode): Migrated from isValidWeakHandle,
        and beefed this up a bit.

        * collector/handles/HandleHeap.h:
        (JSC::HandleHeap::globalData): Added accessor, used by some new set functions.

        * collector/handles/Local.h: Moved hash traits to the bottom of the file,
        since this file is about the Local class, not the traits.

        (JSC::::Local): Updated for removal of invalidate().

        (JSC::::operator): Deployed "using" to avoid a lot of this->
        template funny business.

        (JSC::::setWithSlotCheck): Renamed from internalSet, more specific now.

        * interpreter/RegisterFile.h:
        (JSC::RegisterFile::RegisterFile): Updated to use null constructor.

        * jit/JITStubs.cpp:
        (JSC::JITThunks::hostFunctionStub):

        * runtime/JSPropertyNameIterator.h:
        (JSC::Structure::setEnumerationCache):
        * runtime/Structure.h: Removed clearEnumerationCache
        because it was an unused holdover from when the enumeration cache was
        not a handle.

        * runtime/WeakGCMap.h:
        (JSC::WeakGCMap::set): Finish initializing our handle before putting it
        in the table. This seemed more logical, and at one point was required
        to avoid triggering an ASSERT.

        * runtime/WeakGCPtr.h: Inherit from Handle instead of rolling our own
        handle-like behavior, to avoid duplication.

        (JSC::WeakGCPtr::WeakGCPtr):
        (JSC::WeakGCPtr::~WeakGCPtr):
        (JSC::WeakGCPtr::get):
        (JSC::WeakGCPtr::clear):
        (JSC::WeakGCPtr::set):
        (JSC::WeakGCPtr::setWithWriteBarrier): Removed duplicate code and
        standardized on Handle idioms.
2011-04-07  Geoffrey Garen  <ggaren@apple.com>

        Reviewed by Maciej Stachowiak.

        Some Handle<T> cleanup
        https://bugs.webkit.org/show_bug.cgi?id=58109

        * JSRun.h:
        * JSValueWrapper.h: #include a file that was missing before, but was
        harmlessly so until now.
2011-04-07  Geoffrey Garen  <ggaren@apple.com>

        Reviewed by Maciej Stachowiak.

        Some Handle<T> cleanup
        https://bugs.webkit.org/show_bug.cgi?id=58109

        * bindings/js/ScriptValue.h:
        (WebCore::ScriptValue::ScriptValue): Updated for new null constructor.
        (WebCore::ScriptValue::hasNoValue): Updated for removal of isEmpty().
2011-04-07  Geoffrey Garen  <ggaren@apple.com>

        Some Handle<T> cleanup
        https://bugs.webkit.org/show_bug.cgi?id=58109

        * WebProcess/Plugins/Netscape/NPJSObject.cpp:
        (WebKit::NPJSObject::NPJSObject): Updated for new null constructor.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@83259 268f45cc-cd09-0410-ab3c-d52691b4dbfc