layout: Scale images in image_set by their specified resolution (#36374)

This PR makes it so the `resolution` factor in `image-set` also affects
the image size.
For instance, in the example below:

```css
background-image: image-set("./small.png" 1x, "./large.png" 2x);
```

if `large.png` is used, an image which is 32x32 will be rendered as
16x16. This is specified
in <https://drafts.csswg.org/css-images-4/#image-set-notation>.

Testing:
 - `css/css-images/image-set/image-set-resolution-002.html`

---------

Signed-off-by: tobinio <Tobias.frischmann1@gmail.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Josh Matthews <josh@joshmatthews.net>

tests/wpt/meta/css/css-images/image-set/image-set-resolution-002.html.ini

@@ -1,2 +0,0 @@
-[image-set-resolution-002.html]
-  expected: FAIL