blink: changes min size for webkit-box

webkit-box treats a min-size of auto as 0. This adds that logic
to FlexLayoutAlgorithm.

BUG=993813
TEST=fast/css/deprecated-flexbox-auto-min-size.html

Change-Id: I80eb42616575891d4a99450f6d1fd515ba3c39a9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1799389Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695840}

third_party/blink/renderer/core/layout/flexible_box_algorithm.cc

@@ -592,6 +592,12 @@ bool FlexLayoutAlgorithm::ShouldApplyMinSizeAutoForChild(
   if (!min.IsAuto())
     return false;
 
+  // webkit-box treats min-size: auto as 0.
+  if (StyleRef().Display() == EDisplay::kWebkitBox ||
+      StyleRef().Display() == EDisplay::kWebkitInlineBox) {
+    return false;
+  }
+
   return !child.ShouldApplySizeContainment() &&
          !child.DisplayLockInducesSizeContainment() &&
          MainAxisOverflowForChild(child) == EOverflow::kVisible;