Debugger: Initialize treeview slider position backup properly

Change-Id: I587ce51475e7cc96229fe9619e705f51134b6462
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/watchwindow.cpp

@@ -474,7 +474,7 @@ static void addStackLayoutMemoryView(DebuggerEngine *engine, bool separateView,
 /////////////////////////////////////////////////////////////////////
 
 WatchTreeView::WatchTreeView(WatchType type)
-  : m_type(type)
+  : m_type(type), m_sliderPosition(0)
 {
     setObjectName(QLatin1String("WatchWindow"));
     m_grabbing = false;