[css-flexbox] Better test for min-height in nested flexboxes

This adds a much better testcase for bug 580196 -- this is a reduced version
of the original testcase for that bug, to ensure that we don't regress the
actual issue (which I almost did in https://codereview.chromium.org/2157093002/)

The testcase that I'm replacing was just verifying that we don't apply
min-height: auto to nested flexboxes, which is not very valuable.

BUG=580196
R=eae@chromium.org,dgrogan@chromium.org

Review-Url: https://codereview.chromium.org/2156403002
Cr-Commit-Position: refs/heads/master@{#406156}
1 file changed