Bug 1626146: Adjust expected height in WPT test flexitem-stretch-image.html to account for image hypothetical height being influenced by its used main size. r=cbiesinger

This makes the test pass in Gecko and EdgeHTML and fail in Chromium/WebKit.
The test-failure is due to an underlying bug that these engines share, which is
filed as:
https://bugs.chromium.org/p/chromium/issues/detail?id=721123
https://bugs.webkit.org/show_bug.cgi?id=209983

Differential Revision: https://phabricator.services.mozilla.com/D69635

--HG--
extra : moz-landing-system : lando

testing/web-platform/meta/css/css-flexbox/flexitem-stretch-image.html.ini

@@ -1,4 +0,0 @@
-[flexitem-stretch-image.html]
-  [.flexbox 1]
-    expected: FAIL
-

testing/web-platform/tests/css/css-flexbox/flexitem-stretch-image.html

@@ -28,8 +28,8 @@ to fit the size of flexitem according to flex values.">
 <div id=log></div>
 
 <div class="flexbox">
-  <img data-expected-display="block" data-expected-width="345" style="flex: 1 0 auto;" src="support/100x100-blue.png">
-  <img data-expected-display="block" data-expected-width="255" data-expected-height="100" style="flex: 1 0 auto;" src="support/10x10-green.png">
+  <img data-expected-display="block" data-expected-width="345" data-expected-height="345" style="flex: 1 0 auto;" src="support/100x100-blue.png">
+  <img data-expected-display="block" data-expected-width="255" data-expected-height="345" style="flex: 1 0 auto;" src="support/10x10-green.png">
 </div>
 
 </body>