Snapshotter scales incorrectly

[1ec5]

If I create an MGLMapSnapshotOptions object with size set to 456×480 on a 2× display, MGLMapSnapshotter produces an image 1,824 pixels wide by 1,920 pixels tall, which is what I would expect on a 4× display if MGLMapSnapshotOptions.size were measured in points (#10088). As the property is currently documented, however, a size of 456×480 should result in a 456×480-pixel image regardless of the screen resolution.

/ref #10020 (comment)
/cc @fabian-guerra @frederoni

[fabian-guerra]

As #10020 (comment) we do handle internally the scale. The output image is scaled accordingly. 456x480 will scale as 1:1 on non-retina screens otherwise will be 1824x1920 px on a 4× display.

[1ec5]

Regardless of whether we internally handle the scale, MGLMapSnapshotter is incorrectly scaling the output image. The example above was on a 2× display, not a 4× display, yet MGLMapSnapshotter was behaving as if it was on a 4× display and size was measured in points. 456×480 pixels should mean 456×480 pixels regardless of screen resolution.