small doc-block typo
fix candidate selection

previous ascendingSort() wasn’t doing much, since not returning -1 when
resolution ‘a’ was smaller than that of ‘b’. I fixed this ( - instead
of >) but also resorted to ascending sorting.

The logic now goes that we start with the highest resolution available,
then go down gradually until we find the last one that is above the
Dpr. This solves the situation where all available images are below Dpr
(previously the lowest candidate would have been served, now the
highest is being served)
fix elements selection

In browsers that support srcset, don’t exclude img elements that also
have a ‘sizes’ attribute, which isn’t supported for now. We should add
precise feature detection, really.

+ wondering how we can manage when `400w` is used in srcset but
`sizes=“100vw”` is implied but omitted (this isn’t supported by any
browser either afaik)
Merge branch 'fix-candidate-selection' into refactor
Merge branch 'small-typo' into refactor
compress latest commits
fix candidate selection and sourceSize splitting