Debugger: Use Utils::TreeModel for watch window

The circle closes, that's where the code came from.

Change-Id: Ic36ab61ec8886c9a2747aeb29a7245df3ef0b6c4
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/watchdata.h

@@ -98,6 +98,7 @@ public:
     bool isVTablePointer() const;
 
     bool isEqual(const WatchData &other) const;
+    bool isAncestorOf(const QByteArray &childIName) const;
 
     void setError(const QString &);
     void setValue(const QString &);