[flex] Don't stretch orthog. flex-items in column flexboxes.

Delete code - pass tests!

"!ShouldItemShrinkToFit()" was returning true for an orthogonal item
within a column flexbox. This in turn was getting it to stretch when
it shouldn't have. We now already set the "stretch" bit in the
appropriate places when stretching is occurring (previously stretch was
the default, not shrink-to-fit).

This removes the bad branch, and the complicated ShouldItemShrinkToFit()
function!

Bug: 1189046
Change-Id: Ib4b8762ce2999fe3690f9aa16d1925de53ce13a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2773659
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Reviewed-by: David Grogan <dgrogan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#865412}
diff --git a/css/css-flexbox/flexbox_align-items-center-3.html b/css/css-flexbox/flexbox_align-items-center-3.html
new file mode 100644
index 0000000..b140cd1
--- /dev/null
+++ b/css/css-flexbox/flexbox_align-items-center-3.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
+<link rel="match" href="../reference/ref-filled-green-100px-square-only.html">
+<meta name="assert" content="This checks that an orthogonal flex-item with center alignment doesn't stretch.">
+<p>Test passes if there is a filled green square.</p>
+<style>
+.container {
+  margin-left: -50px;
+  width: 200px;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+}
+
+.child {
+  writing-mode: vertical-rl;
+  height: 100px;
+  background: green;
+}
+</style>
+<div class="container">
+  <div class="child">
+    <div style="width: 100px;"></div>
+  </div>
+</div>