Fix fatal error caused by calling i18n in another thread initiated by webkit

The related backtrace is:

QtCore4.dll!qfatal
libkdecore.dll!KGlobal::locale
libkdecore.dll!KDETranslator::translate
QtCore4.dll!QTranslator::translate
QtCore4.dll!QCoreApplication::translate
QtCore4.dll!QCoreApplication::translate
QtWebKit4.dll!DumpRenderTreeSupportQt::addURLToRedirect
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPluginDatabase::qt_metacall
QtWebKit4.dll!QWebPage::~QWebPage
QtWebKit4.dll!QWebPage::~QWebPage
QtWebKit4.dll!QWebView::QWebView
QtWebKit4.dll!QWebView::QWebView
QtWebKit4.dll!QWebView::~QWebView
libalkimia-8.dll!AlkWebPage::~AlkWebPage