This is the old code path that creates the thumbnail and preview image the hard way. Since it is now being used only for non-jpeg images, we can't use #-moz-samplesize anyway, so it is fine to fall back on this existing code.

This old code is actuallly more efficient that calling cropResizeRotate twice to create both a preview and a thumbnail image because createThumbnailAndPreview only decodes the fullsize image once to create both smaller sizes.