Fix flex item with intrinsic aspect ratio

[shinglyu]

Quote @stshine

flex item with intrinsic aspect ratio
Item like image that have its intrinsic ratio needs special handling to keep its ratio after flex lengths resolving. Currently servo handle them in https://github.com/servo/servo/blob/master/components/layout/fragment.rs#L488 , which get the size info directly from style, thus won't fit into flexbox. That method needs to be changed, maybe isolating logic for intrinsic aspect ratio is good idea.

Maybe related? https://github.com/servo/servo/pull/14490/files

[shinglyu]

https://drafts.csswg.org/css-flexbox/#algo-main-item (?)

[stshine]

Yeah, now you can know whether a fragment has intrinsic aspect ratio by the has_intrinsic_ratio() method. And you may need to isolate some code from calculate_replaced_sizes() and reuse the logic.

[shinglyu]

The css-test test cases are blocked by #15402, I'll take a look at that first.