Return the correct geometry

When the platform window is created, it is the
authorative source for geometry information.

It would however be better if we could completely
avoid duplicated places for the geometry data.

Change-Id: Id90b24b9c40acb57f3d11b8b927292c06bac335e
Reviewed-on: http://codereview.qt-project.org/5258
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

src/gui/kernel/qwindow.cpp

@@ -425,6 +425,8 @@ void QWindow::setGeometry(const QRect &rect)
 QRect QWindow::geometry() const
 {
     Q_D(const QWindow);
+    if (d->platformWindow)
+        return d->platformWindow->geometry();
     return d->geometry;
 }