Tests encoding of a response body

Results for /resources/square200.png encoding=jpeg q=undefined sizeOnly=undefined
body=string body.length~18100
original=15506 encoded~13600

Results for /resources/square200.png encoding=webp q=0.8 sizeOnly=false
body=string body.length~1200
original=15506 encoded~900

Results for /resources/square200.png encoding=jpeg q=1 sizeOnly=true
body=undefined body.length~undefined
original=15506 encoded~13600

Results for /resources/square200.png encoding=jpeg q=0.5 sizeOnly=true
body=undefined body.length~undefined
original=15506 encoded~1200

Results for /resources/square20.bmp encoding=jpeg q=0.8 sizeOnly=true
body=undefined body.length~undefined
original=1322 encoded~300

Results for /resources/square20.bmp encoding=png q=undefined sizeOnly=undefined
body=string body.length~200
original=1322 encoded~100

Results for /resources/load-and-stall.php?name=dummy.html&mimeType=image%2Fpng encoding=png q=undefined sizeOnly=undefined
failed to determine