Above, you should see an animating SVG. Below that a horizontal line. And below that, a (big) JPG image will appear.
The SVG child is very small in document size. It should load quickly and immediately run a declarative animation (a blue progress bar, that appears above the horizontal line). The JPG image, OTOH, is much larger in file size and it should take a bit longer to load. (You might need to clear your browser cache, to see the effect.)
In essence, the SVG animation is supposed to entertain the user, while the big raster image is still loading.
In case SVG scripting is supported (which is not required for this test), a green hook should appear in the SVG (below the blue progress bar, but above the horizontal line), after the JPG has loaded.
However, a red "X" may also appear, indicating, that this test has failed. If you see a red "X", then this means, that "declarative animations while raster image is loading" is not supported. Please note, that this test may also fail for various other reasons. For example, the test has failed, if the SVG animation is starting only after the raster image has finished loading. The test has also failed, if no progressbar is being shown in the SVG (maybe because declarative animations are not supported).