[css-flexbox] Don't apply min-height: auto to children with percentage heights

In such a case, we compute an incorrect intrinsic logical height, because
we resolve pre-flex percentages when we calculate the intrinsic height.
In common cases this can be 100% of the flexbox height, which we later
use as a min-height of the flex item, leading to it not shrinking when
it should.

This reverts https://crrev.com/c/1269235 for the case of a flex item
which is a flexbox with percentage children.

Bug: 927066
Change-Id: I955bf651f75495122bb454d5221303b188bbb03c
Reviewed-on: https://chromium-review.googlesource.com/c/1452477
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Auto-Submit: Christian Biesinger <cbiesinger@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#628806}(cherry picked from commit 4f73107eed2d8f61e189dcd52239159129961750)
Reviewed-on: https://chromium-review.googlesource.com/c/1452490
Reviewed-by: Abdul Syed <abdulsyed@google.com>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Cr-Commit-Position: refs/branch-heads/3693@{#6}
Cr-Branched-From: 58322e3f2f0c240b91b56bc9039cd989b201b557-refs/heads/master@{#628647}
2 files changed