Drop windowId property from PlasmaCore.Dialog

Property windowId was according to the comments only provided because
KWin needed it. KWin's usecase was to know the window Id of the window
where a given item is rendered to. In QtQuick a QQuickItem provides a
pointer to the QQuickWindow holding the item. This means this hack is no
longer needed.

REVIEW: 112033

src/declarativeimports/core/dialog.cpp

@@ -301,13 +301,6 @@ int DialogProxy::windowFlags() const
     return (int)m_flags;
 }
 
-#ifndef Q_WS_WIN
-qulonglong DialogProxy::windowId() const
-{
-    return winId();
-}
-#endif
-
 void DialogProxy::setWindowFlags(const int flags)
 {
     m_flags = (Qt::WindowFlags)flags;

src/declarativeimports/core/dialog.h

@@ -79,13 +79,6 @@ class DialogProxy : public QQuickWindow
      * Plasma Location of the dialog window. Useful if this dialog is apopup for a panel
      */
     Q_PROPERTY(int location READ location WRITE setLocation NOTIFY locationChanged)
-//This won't be available on windows, but should be used only by kwin and never by applets anyways
-#ifndef Q_WS_WIN
-    /**
-     * Window ID of the dialog window.
-     **/
-    Q_PROPERTY(qulonglong windowId READ windowId CONSTANT)
-#endif
 
     Q_CLASSINFO("DefaultProperty", "mainItem")
 
@@ -123,10 +116,6 @@ public:
 
     QObject *margins() const;
 
-#ifndef Q_WS_WIN
-    qulonglong windowId() const;
-#endif
-
     /**
      * @returns The suggested screen position for the popup
      * @arg item the item the popup has to be positioned relatively to. if null, the popup will be positioned in the center of the window