QmlDebugger: Insert locals correctly

The watchhandler needs to be reset for locals before
inserting the values of a new frame. Also the DebuggerTooltipManager
needs to be notified. The values of the locals in the
LocalsAndExpressions window should be editable.

Task-number: QTCREATORBUG-7992
Change-Id: I556e23b408db09b510f1f2bc350ff55187ec87c2
Reviewed-by: Robert Loehning <robert.loehning@digia.com>
Reviewed-by: Christiaan Janssen <christiaan.janssen@digia.com>

src/plugins/debugger/qml/qmlinspectoragent.cpp

@@ -885,9 +885,6 @@ bool QmlInspectorAgent::isConnected() const
 
 void QmlInspectorAgent::clearObjectTree()
 {
-    // clear view
-    m_debuggerEngine->watchHandler()->cleanup();
-
     m_objectTreeQueryIds.clear();
     m_fetchDataIds.clear();
     int old_count = m_debugIdHash.count();