main frame - didStartProvisionalLoadForFrame
main frame - didCommitLoadForFrame
main frame - didReceiveTitle: 
main frame - didFinishDocumentLoadForFrame
main frame - didHandleOnloadEventsForFrame
main frame - didFinishLoadForFrame
main frame - didStartProvisionalLoadForFrame
main frame - didCommitLoadForFrame
main frame - didReceiveTitle: 
main frame - didFinishDocumentLoadForFrame
main frame - didHandleOnloadEventsForFrame
main frame - didFinishLoadForFrame
PASS internals.isPreloaded('resources/preload-test.jpg'); is false
PASS internals.isPreloaded('resources/base-image2.png'); is true
PASS internals.isPreloaded('resources/base-image1.png'); is false
PASS internals.isPreloaded('resources/base-image3.png'); is false
PASS internals.isPreloaded('resources/image2.png'); is true
PASS successfullyParsed is true

TEST COMPLETE
This test passes if the fallback image (defined in the href attribute) is not preloaded, but the 2x version (defined in imagesrcset) is.
The second link rel=preload is here to make sure isPreloaded is working properly