[css-flexbox] Move min-size-auto.html from css3/flexbox to WPT

This CL migrates this test out of
third_party/blink/web_tests/css3/flexbox and into the WPT-specific
directory, adding links to the relevant specs and a test assertion
describing its purpose and renames it to
flex-minimum-size-002.html

Bug: 1063749
Change-Id: I1bb8d941d41a61c984b6431808302eb3d051a50a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2123500
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: David Grogan <dgrogan@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754073}
diff --git a/third_party/blink/web_tests/css3/flexbox/min-size-auto.html b/third_party/blink/web_tests/external/wpt/css/css-flexbox/flex-minimum-size-002.html
similarity index 67%
rename from third_party/blink/web_tests/css3/flexbox/min-size-auto.html
rename to third_party/blink/web_tests/external/wpt/css/css-flexbox/flex-minimum-size-002.html
index 0959549..c2eea80 100644
--- a/third_party/blink/web_tests/css3/flexbox/min-size-auto.html
+++ b/third_party/blink/web_tests/external/wpt/css/css-flexbox/flex-minimum-size-002.html
@@ -1,9 +1,16 @@
 <!DOCTYPE html>
-<link href="resources/flexbox.css" rel="stylesheet">
+<title>CSS Flexbox: flexbox with min-size: auto</title>
+<link rel="help" href="https://drafts.csswg.org/css-flexbox/#flex-containers">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox/#flex-direction-property">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox/#min-size-auto">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox/#flex-basis-property">
+<link rel="bookmark" href="https://crbug.com/426898">
+<link href="support/flexbox.css" rel="stylesheet">
+<meta name="assert" content="Flexbox with min-size: auto is handled correctly.">
 
-<script src="../../resources/testharness.js"></script>
-<script src="../../resources/testharnessreport.js"></script>
-<script src="../../resources/check-layout-th.js"></script>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
 
 <style>
 .flexbox {