[css-flexbox] Improve sizing in column layout
This patch implements intrinsic sizing for column flex containers.
It also removes inline_content_sizes() from FlexItemBox, in favour of
outer_inline_content_sizes() from IndependentFormattingContext, which
now accepts a new parameter to resolve automatic minimum sizes.
Also some fixes during the layout of flex items in a column layout.
Signed-off-by: Oriol Brufau obrufau@igalia.com