[css-grid] Fix behavior of flexible track breadths
This patch is fixing 2 issues that are interrelated:
* Flex sizes are invalid on the min slot of minmax().
The syntax has been recently updated on the spec:
minmax( <inflexible-breadth> , <track-breadth> )
To fix this, the patch modifies consumeGridBreadth()
in CSSPropertyParser, adding a new type of restriction
* Flex sizes outside minmax() behave as auto minimum.
Flex sizes outside minmax() were previously behaving like
minimum and maximum (e.g. 1fr => minmax(1fr, 1fr)).
However the spec changed and now this would be invalid,
so they should behave like auto minimum (e.g. minmax(auto, 1fr)).
To achieve this the patch adds a new condition in
The patch includes new test cases checking specifically these 2 issues.
In addition several tests results have been updated to reflect
the new behavior. Also, some cases that are now invalid and
were not testing anything new have been removed.