Priority hint LCP experiment stopped showing unless the image has a fetchPriority attr already

[scottjehl]

I think this change knocked it out of the suggestions for any image that doesn't have a fetchPriority attribute in the markup.
b7931d2

Both of these work instead.

if (!$isBG && !$isVideo && !isset($lcp['element']['fetchPriority']) || $lcp['element']['fetchPriority'] != 'high') {

or
if (!$isBG && !$isVideo && !(isset($lcp['element']['fetchPriority']) && $lcp['element']['fetchPriority'] == 'high')) {

I think the second one is better because we should show this experiment if there's a fetchPriority="low" on there for some reason.