Only accept direct child imgs when determing If picture is loaded

[RevisionTen]

Otherwise it won't work If the picture element has a fallback img inside of a script tag (the img in the script tag is selected and no new img element is appended to the picture element).

This fix is needed when dynamically adding picture elements with fallback img in a noscript tag.

[RevisionTen]

Maybe this can also be fixed with a call to isLoaded instead.

[ApoorvSaxena]

@RevisionTen can you please share a codepen example where the existing implementation fails?

[RevisionTen]

@ApoorvSaxena Sure, heres an example where it fails with an img inside a noscript:
https://jsfiddle.net/k4bzp596/

Heres the same code but without the noscript fallback img:
https://jsfiddle.net/7L9qzfwk/

I ran into this problem with a site where I load content containing lozad pictures via ajax for visitors that have javascript enabled (visitors without javascript are just opening a new page instead of dynamically loading the content).
A simple workaround was to just remove the noscript element before inserting the picture elements into the DOM (they don't need them anyways because they obviously have javascript enabled).