From 6d77f726d583dbd755a4910dbac253d105aee220 Mon Sep 17 00:00:00 2001
From: Daniel Holbert <dholbert@cs.stanford.edu>
Date: Tue, 21 Jan 2014 14:52:30 -0800
Subject: [PATCH] Bug 783470 part 4: reftests for visibility:collapse on flex
 items. r=mats

---
 ...flexbox-collapsed-item-baseline-1-ref.html |  62 ++++++++++
 .../flexbox-collapsed-item-baseline-1.html    |  54 +++++++++
 .../flexbox-collapsed-item-horiz-1-ref.html   | 102 ++++++++++++++++
 .../flexbox-collapsed-item-horiz-1.html       |  98 ++++++++++++++++
 .../flexbox-collapsed-item-horiz-2-ref.html   | 108 +++++++++++++++++
 .../flexbox-collapsed-item-horiz-2.html       | 111 ++++++++++++++++++
 .../flexbox-collapsed-item-horiz-3-ref.html   |  46 ++++++++
 .../flexbox-collapsed-item-horiz-3.html       |  56 +++++++++
 .../w3c-css/submitted/flexbox/reftest.list    |   6 +
 9 files changed, 643 insertions(+)
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1-ref.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1-ref.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2-ref.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3-ref.html
 create mode 100644 layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3.html
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1-ref.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1-ref.html
new file mode 100644
index 000000000000..60da9430d411
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1-ref.html
@@ -0,0 +1,62 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- In this reference case, we get each container to be sized the same as
+     in the testcase, without any visible baseline alignemnt, by using some
+     hidden flex items.
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      width: 50px;
+      background: yellow;
+      border: 1px dotted black;
+      margin: 5px;
+      align-items: flex-start;
+    }
+    .hiddenItemForSizing {
+      width: 0;
+      color: transparent;
+      align-self: baseline;
+    }
+    .largeFont {
+      font-size: 20px;
+      background: lightblue;
+      /* Our flex items get padding on opposite sides (top/bottom) so that they
+         produce a large combined height when baseline-aligned: */
+      padding-top: 5px;
+    }
+    .smallFont {
+      font-size: 10px;
+      background: pink;
+      /* Our flex items get padding on opposite sides (top/bottom) so that they
+         produce a large combined height when baseline-aligned: */
+      padding-bottom: 20px;
+    }
+  </style>
+</head>
+<body>
+  <div class="flexContainer">
+    <div class="largeFont">a</div>
+    <!-- Hidden flex items used to determine container's cross size,
+         based on their baseline-aligned combined cross size: -->
+    <div class="largeFont hiddenItemForSizing">a</div>
+    <div class="smallFont hiddenItemForSizing">b</div>
+  </div>
+
+  <div class="flexContainer">
+    <div class="smallFont">b</div>
+    <!-- Hidden flex items used to determine container's cross size,
+         based on their baseline-aligned combined cross size: -->
+    <div class="largeFont hiddenItemForSizing">a</div>
+    <div class="smallFont hiddenItemForSizing">b</div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1.html
new file mode 100644
index 000000000000..0ce882cf7630
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-baseline-1.html
@@ -0,0 +1,54 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Test: Testing that a collapsed flex item participates in baseline alignment only for the purpose of establishing container's cross size</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="http://www.w3.org/TR/css3-flexbox/#algo-visibility">
+  <link rel="match" href="flexbox-collapsed-item-baseline-1-ref.html">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      width: 50px;
+      background: yellow;
+      border: 1px dotted black;
+      margin: 5px;
+      align-items: baseline;
+    }
+    .collapse {
+      visibility: collapse;
+    }
+    .largeFont {
+      font-size: 20px;
+      background: lightblue;
+      /* Our flex items get padding on opposite sides (top/bottom) so that they
+         produce a large combined height when baseline-aligned: */
+      padding-top: 5px;
+    }
+    .smallFont {
+      font-size: 10px;
+      background: pink;
+      /* Our flex items get padding on opposite sides (top/bottom) so that they
+         produce a large combined height when baseline-aligned: */
+      padding-bottom: 20px;
+    }
+  </style>
+</head>
+<body>
+  <!-- Second item collapsed: -->
+  <div class="flexContainer">
+    <div class="largeFont">a</div>
+    <div class="smallFont collapse">b</div>
+  </div>
+
+  <!-- First item collapsed: -->
+  <div class="flexContainer">
+    <div class="largeFont collapse">a</div>
+    <div class="smallFont">b</div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1-ref.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1-ref.html
new file mode 100644
index 000000000000..90131878421d
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1-ref.html
@@ -0,0 +1,102 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!-- In this reference case, we have blocks in place of the testcase's
+     flex containers. The testcase's collapsed flex items are entirely
+     absent here (and the remaining content is sized using exact pixel
+     values).
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .flexContainer > * {
+      /* All flex items have 20px base size */
+      width: 20px;
+    }
+    .collapse {
+      flex-basis: 0;
+      height: 20px;
+    }
+    .flexible {
+      flex: 1 auto;
+    }
+    .heightTall {
+      height: 40px;
+      background: purple;
+    }
+    .heightAuto {
+      background: teal;
+    }
+    .heightShort {
+      height: 10px;
+      background: pink;
+    }
+  </style>
+</head>
+<body>
+  <!-- FIRST ROW: -->
+  <!-- Just one (collapsed) flex item, which ends up establishing
+       the container's size (even though it's collapsed): -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- SECOND ROW: -->
+  <!-- One collapsed flex item, one short flex item.
+       (Container ends up with collapsed item's height) -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+    <div class="heightShort"></div>
+  </div>
+  <!-- (same, but with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightShort"></div>
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- THIRD ROW: -->
+  <!-- One collapsed flex item, one stretched flex item.
+       (Container and stretched item end up with collapsed item's height) -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+    <div class="heightAuto"></div>
+  </div>
+  <!-- (again, with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightAuto"></div>
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- FOURTH ROW: -->
+  <!-- One collapsed flex item, one other flex item; both are flexible.
+       (The non-collapsed one should take all of the available width.) -->
+  <div class="flexContainer">
+    <div class="heightAuto collapse"></div>
+    <div class="heightTall flexible"></div>
+  </div>
+  <!-- (again, with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightTall flexible"></div>
+    <div class="heightAuto collapse"></div>
+  </div>
+
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1.html
new file mode 100644
index 000000000000..da6c5f144bc8
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-1.html
@@ -0,0 +1,98 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Test: Testing that visibility:collapse on a flex item in a single-line flex container maintains the containers's cross size, but doesn't otherwise impact flex layout</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="http://www.w3.org/TR/css3-flexbox/#algo-visibility">
+  <link rel="match" href="flexbox-collapsed-item-horiz-1-ref.html">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .flexContainer > * {
+      /* All flex items have 20px base size */
+      width: 20px;
+    }
+    .collapse {
+      visibility: collapse;
+    }
+    .flexible {
+      flex: 1 auto;
+    }
+    .heightTall {
+      height: 40px;
+      background: purple;
+    }
+    .heightAuto {
+      background: teal;
+    }
+    .heightShort {
+      height: 10px;
+      background: pink;
+    }
+  </style>
+</head>
+<body>
+  <!-- FIRST ROW: -->
+  <!-- Just one (collapsed) flex item, which ends up establishing
+       the container's size (even though it's collapsed): -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- SECOND ROW: -->
+  <!-- One collapsed flex item, one short flex item.
+       (Container ends up with collapsed item's height) -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+    <div class="heightShort"></div>
+  </div>
+  <!-- (same, but with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightShort"></div>
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- THIRD ROW: -->
+  <!-- One collapsed flex item, one stretched flex item.
+       (Container and stretched item end up with collapsed item's height) -->
+  <div class="flexContainer">
+    <div class="heightTall collapse"></div>
+    <div class="heightAuto"></div>
+  </div>
+  <!-- (again, with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightAuto"></div>
+    <div class="heightTall collapse"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- FOURTH ROW: -->
+  <!-- One collapsed flex item, one other flex item; both are flexible.
+       (The non-collapsed one should take all of the available width.) -->
+  <div class="flexContainer">
+    <div class="heightAuto flexible collapse"></div>
+    <div class="heightTall flexible"></div>
+  </div>
+  <!-- (again, with items in opposite order) -->
+  <div class="flexContainer">
+    <div class="heightTall flexible"></div>
+    <div class="heightAuto flexible collapse"></div>
+  </div>
+
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2-ref.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2-ref.html
new file mode 100644
index 000000000000..a9040e306c8c
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2-ref.html
@@ -0,0 +1,108 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      flex-wrap: wrap;
+
+      /* These let us show where each flex line begins (and hence, how tall
+         the flex lines end up) */
+      align-content: flex-start;
+      align-items: flex-start;
+
+      width: 30px;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .collapsedItem {
+      width: 0;
+      height: 25px;
+    }
+    .halfWidthItem {
+      width: 15px;
+      height: 15px;
+      background: teal;
+    }
+    .fullWidthItem {
+      width: 30px;
+      height: 20px;
+      background: purple;
+    }
+    .veryTallItem {
+      width: 15px;
+      height: 40px;
+      background: olive;
+    }
+  </style>
+</head>
+<body>
+  <!-- FIRST ROW: -->
+  <!-- One collapsed flex item, at the beginning of a flex line, which
+       ends up establishing its flex line's cross size: -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="halfWidthItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <!-- ...and now with it being at the end of that flex line: -->
+  <div class="flexContainer">
+    <div class="halfWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- SECOND ROW: -->
+  <!-- One collapsed flex item, initially in its own line. It ends
+       up being merged into another line after it collapses, due to its
+       (post-collapse) zero main-size. -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- THIRD ROW: -->
+  <!-- One collapsed flex item, initially in a line with an even-taller item.
+       The collapsed item ends up shifting into another line after it
+       collapses, but it carries the taller item's cross size with it, as its
+       strut size. -->
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem" style="height: 40px"></div>
+    <div class="veryTallItem"></div>
+  </div>
+  <!-- ...and now with two (differently-sized) struts in first line:
+       (the one that's taller - due to being initially grouped with the tall
+       item - wins out.) -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem" style="height: 40px"></div>
+    <div class="veryTallItem"></div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2.html
new file mode 100644
index 000000000000..49c3bf1cf096
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-2.html
@@ -0,0 +1,111 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Test: Testing that visibility:collapse on a flex item in a multi-line flex container creates struts, and that they can migrate between lines</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="http://www.w3.org/TR/css3-flexbox/#algo-visibility">
+  <link rel="match" href="flexbox-collapsed-item-horiz-2-ref.html">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      flex-wrap: wrap;
+
+      /* These let us show where each flex line begins (and hence, how tall
+         the flex lines end up) */
+      align-content: flex-start;
+      align-items: flex-start;
+
+      width: 30px;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .collapsedItem {
+      visibility: collapse;
+      width: 15px;
+      height: 25px;
+    }
+    .halfWidthItem {
+      width: 15px;
+      height: 15px;
+      background: teal;
+    }
+    .fullWidthItem {
+      width: 30px;
+      height: 20px;
+      background: purple;
+    }
+    .veryTallItem {
+      width: 15px;
+      height: 40px;
+      background: olive;
+    }
+  </style>
+</head>
+<body>
+  <!-- FIRST ROW: -->
+  <!-- One collapsed flex item, at the beginning of a flex line, which
+       ends up establishing its flex line's cross size: -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="halfWidthItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <!-- ...and now with it being at the end of that flex line: -->
+  <div class="flexContainer">
+    <div class="halfWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- SECOND ROW: -->
+  <!-- One collapsed flex item, initially in its own line. It ends
+       up being merged into another line after it collapses, due to its
+       (post-collapse) zero main-size. -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+  </div>
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+  </div>
+
+  <div style="clear: both"></div>
+
+  <!-- THIRD ROW: -->
+  <!-- One collapsed flex item, initially in a line with an even-taller item.
+       The collapsed item ends up shifting into another line after it
+       collapses, but it carries the taller item's cross size with it, as its
+       strut size. -->
+  <div class="flexContainer">
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="veryTallItem"></div>
+  </div>
+  <!-- ...and now with two (differently-sized) struts in first line:
+       (the one that's taller - due to being initially grouped with the tall
+       item - wins out.) -->
+  <div class="flexContainer">
+    <div class="collapsedItem"></div>
+    <div class="fullWidthItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="veryTallItem"></div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3-ref.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3-ref.html
new file mode 100644
index 000000000000..c8242106ba14
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3-ref.html
@@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Reftest Reference</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      flex-wrap: wrap;
+      align-content: stretch; /* Initial value; just here for emphasis */
+      width: 25px;
+      height: 60px;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .collapsedItem {
+      width: 0;
+      height: 40px;
+    }
+    .shortItem {
+      width: 25px;
+      height: 10px;
+      background: purple;
+    }
+    .tallItem {
+      width: 10px;
+      height: 30px;
+      background: olive;
+    }
+  </style>
+</head>
+<body>
+  <div class="flexContainer">
+    <div class="shortItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="tallItem"></div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3.html b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3.html
new file mode 100644
index 000000000000..f8811c35b91e
--- /dev/null
+++ b/layout/reftests/w3c-css/submitted/flexbox/flexbox-collapsed-item-horiz-3.html
@@ -0,0 +1,56 @@
+<!DOCTYPE html>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>CSS Test: Testing that strut formation (from visibility:collapse) happens *after* lines have been stretched</title>
+  <link rel="author" title="Daniel Holbert" href="mailto:dholbert@mozilla.com">
+  <link rel="help" href="http://www.w3.org/TR/css3-flexbox/#algo-visibility">
+  <link rel="match" href="flexbox-collapsed-item-horiz-3-ref.html">
+  <meta charset="utf-8">
+  <style>
+    .flexContainer {
+      display: flex;
+      flex-wrap: wrap;
+      align-content: stretch; /* Initial value; just here for emphasis */
+      width: 25px;
+      height: 60px;
+      background: yellow;
+      border: 1px dotted black;
+      float: left;
+      margin: 5px;
+    }
+    .collapsedItem {
+      visibility: collapse;
+      width: 10px;
+    }
+    .shortItem {
+      width: 25px;
+      height: 10px;
+      background: purple;
+    }
+    .tallItem {
+      width: 10px;
+      height: 30px;
+      background: olive;
+    }
+  </style>
+</head>
+<body>
+  <!-- In this testcase, the first flex line initially has a cross-size of
+       10px, and the second flex line has a cross-size of 30px. Both lines are
+       stretched by 10px each (to hit the container's total cross-size, 60px).
+       Then, we handle "visibility:collapse" and convert the collapsed item
+       into a strut with the second line's stretched cross-size (40px), and we
+       restart flex layout. This strut then ends up in the *first* line (since
+       it has 0 main-size), which means both flex lines end up being 40px tall.
+    -->
+  <div class="flexContainer">
+    <div class="shortItem"></div>
+    <div class="collapsedItem"></div>
+    <div class="tallItem"></div>
+  </div>
+</body>
+</html>
diff --git a/layout/reftests/w3c-css/submitted/flexbox/reftest.list b/layout/reftests/w3c-css/submitted/flexbox/reftest.list
index ca894672fa89..14e26487c3d6 100644
--- a/layout/reftests/w3c-css/submitted/flexbox/reftest.list
+++ b/layout/reftests/w3c-css/submitted/flexbox/reftest.list
@@ -77,6 +77,12 @@ fuzzy-if(Android,158,32) == flexbox-align-self-vert-rtl-1.xhtml  flexbox-align-s
 == flexbox-break-request-vert-2a.html  flexbox-break-request-vert-2-ref.html
 == flexbox-break-request-vert-2b.html  flexbox-break-request-vert-2-ref.html
 
+# Tests for flex items with "visibility:collapse"
+== flexbox-collapsed-item-baseline-1.html flexbox-collapsed-item-baseline-1-ref.html
+== flexbox-collapsed-item-horiz-1.html flexbox-collapsed-item-horiz-1-ref.html
+== flexbox-collapsed-item-horiz-2.html flexbox-collapsed-item-horiz-2-ref.html
+== flexbox-collapsed-item-horiz-3.html flexbox-collapsed-item-horiz-3-ref.html
+
 # Tests for flex-flow shorthand property
 == flexbox-flex-flow-1.html flexbox-flex-flow-1-ref.html
 
