Don't go through the doScaledRead path (i.e. calling read_image_scaled)
when reading an image that the target size is the image of the file we
are opening.
This makes the loading of the file much faster while keeping the output
correct.
[ChangeLog][QtGui][QImage] Improve loading time when loading png files
that have the same size as the target.
Change-Id: I2a33c49fe1ce52ec296c2175ee542b5bcdec2c4b
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
cc13b99781