[css-flexbox] Better handle percentages for min-height:auto

We only need to ignore percentages when the flex item has a
definite height; if it doesn't, percentages get treated as
height: auto which is the desired behavior. This fixes the two
regressions that were filed because of this.

Bug: 984606, 981481
Change-Id: I008d9ec316e4ff233eac03ead30f09ed85c4c120
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1705578
Auto-Submit: Christian Biesinger <cbiesinger@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#678379}
3 files changed