Image initialized as SWT.ICON in Image(Device, ImageData, ImageData)
loses its "Icon" properties, i.e. type, mask etc., when a handle for a
different zoom level is requested and "SMOOTH" scaling is used. This
change adapts the initialization of the image when the handle is
requested for image type SWT.ICON to preserve the properties.

Fixes https://github.com/eclipse-platform/eclipse.platform.swt/issues/1805