qmlviewer resizes the root object multiple times.

qmlviewer resizes the root object multiple times.

In SizeRootObjectToView mode on initial load the view was set to
root object size, then the sceneResized() slot would resize back,
then we would finally reset back to the correct value in
statusChanged(true).  Now react directly to the initial size being
set.

Change-Id: Ib6977cf7bad3fe79b9ac80bb6d916fb0f57c5f5e
Fixes: QTBUG-16499
Reviewed-on: http://codereview.qt.nokia.com/2148
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>