QmlJsDelta: support for resetting property

... with a little bit of refactoring.

But for some reason it does not seem to have an effect

src/plugins/qmljsinspector/qmljsclientproxy.h

@@ -57,6 +57,7 @@ public:
                              bool isLiteralValue);
 
     bool setMethodBodyForObject(int objectDebugId, const QString &methodName, const QString &methodBody);
+    bool resetBindingForObject(int objectDebugId, const QString &propertyName);
 
     // returns the object references for the given url.
     QList<QDeclarativeDebugObjectReference> objectReferences(const QUrl &url = QUrl()) const;