Initialize member variables during construction

avoids uninitialized memory accesses later on

src/gtk/webview_webkit2.cpp

@@ -490,6 +490,9 @@ bool wxWebViewWebKit::Create(wxWindow *parent,
                       long style,
                       const wxString& name)
 {
+    m_web_view = NULL;
+    m_dbusServer = NULL;
+    m_extension = NULL;
     m_busy = false;
     m_guard = false;
     m_creating = false;