Reviewed by Geoff and Brady.

        - fix <rdar://problem/5680469> Each database worker thread takes a JSLock,
          which slows down all JavaScript execution until the thread terminates

        * bindings/js/JSCustomSQLTransactionCallback.cpp:
        (WebCore::JSCustomSQLTransactionCallback::JSCustomSQLTransactionCallback):
        Explicitly gcProtect, since we aren't using ProtectedPtr any more.
        (WebCore::unprotectOnMainThread): Added.
        (WebCore::JSCustomSQLTransactionCallback::~JSCustomSQLTransactionCallback):
        Use unprotectOnMainThread rather than doing a gcUnprotect here.
        * bindings/js/JSCustomSQLTransactionCallback.h: Changed m_callback from
        a ProtectedPtr to a plain old JSObject*; we gcProtect by hand now.

        * loader/icon/IconDatabase.cpp:
        (WebCore::IconDatabase::notifyPendingLoadDecisionsOnMainThread):
        Renamed. Changed to takea a void* with the icon database pointer.
        (WebCore::IconDatabase::notifyPendingLoadDecisions): Renamed.
        (WebCore::IconDatabase::performURLImport): Updated name, and pass the
        icon database pointer in.
        * loader/icon/IconDatabase.h: Renamed and added void* parameter.

        * platform/Threading.h: Changed callOnMainThread to take a function with a
        single parameter rather than a function with no parameters. Added a typedef.

        * platform/gtk/ThreadingGtk.cpp:
        (WebCore::callFunctionOnMainThread): Changed to use a structure with both
        a function pointer and a context pointer, and delete it after calling.
        (WebCore::callOnMainThread): Changed to create the structure with both
        the function and context pointer.

        * platform/mac/Threading.mm:
        (-[WebCoreFunctionWrapper initWithFunction:context:]): Added context.
        (-[WebCoreFunctionWrapper invoke]): Updated to do both function and context.
        Renamed from _call.
        (WebCore::callOnMainThread): Updated to take both function and context.

        * platform/qt/ThreadingQt.cpp:
        (WebCore::PerformFunctionEvent::PerformFunctionEvent): Added context.
        (WebCore::PerformFunctionEvent::invoke): Added. Calls function with context pointer.
        (WebCore::MainThreadInvoker::event): Changed to call invoke.
        (WebCore::callOnMainThread): Updated to take both function and context.

        * platform/win/ThreadingWin.cpp: Added FunctionWithContext.
        (WebCore::callFunctionsOnMainThread): Changed to pass call function with context.
        (WebCore::callOnMainThread): Updated to queue both function and context.

        * platform/wx/ThreadingWx.cpp:
        (WebCore::callOnMainThread): Updated to take both function and context.

        * storage/Database.cpp:
        (WebCore::Database::scheduleTransactionCallback): Pass 0 for context.
        (WebCore::Database::deliverAllPendingCallbacks): Changed to take ignored context pointer.
        * storage/Database.h: Added void* parameter to deliverAllPendingCallbacks.

        * storage/DatabaseTracker.cpp:
        (WebCore::DatabaseTracker::scheduleForNotification): Pass 0 for context.
        (WebCore::DatabaseTracker::notifyDatabasesChanged): Changed to take ignored context pointer.
        * storage/DatabaseTracker.h: Added void* parameter to notifyDatabasesChanged.

WebKit/win:

        - fix <rdar://problem/5680469> Each database worker thread takes a JSLock,
          which slows down all JavaScript execution until the thread terminates

        * WebIconDatabase.cpp:
        (WebIconDatabase::scheduleNotificationDelivery): Updated for new callOnMainThread.
        (WebIconDatabase::deliverNotifications): Ditto.
        * WebIconDatabase.h: Ditto.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@29922 268f45cc-cd09-0410-ab3c-d52691b4dbfc