[CSS Grid Layout] New alignment related repaint layout tests.

LayoutTests/fast/repaint/align-content-position-change-grid.html

Index: LayoutTests/fast/repaint/align-content-position-change-grid.html
diff --git a/LayoutTests/fast/repaint/align-content-change.html b/LayoutTests/fast/repaint/align-content-position-change-grid.html
similarity index 58%
copy from LayoutTests/fast/repaint/align-content-change.html
copy to LayoutTests/fast/repaint/align-content-position-change-grid.html
index e96b5f72800e326c1c279dae5be73626d93f1a7b..8555d58310d5bef3663828ba2a984029b0bfc69e 100644
--- a/LayoutTests/fast/repaint/align-content-change.html
+++ b/LayoutTests/fast/repaint/align-content-position-change-grid.html
@@ -2,7 +2,7 @@
 <script src="resources/text-based-repaint.js"></script>
 <script>
 function repaintTest() {
-  document.getElementById('container').style.alignContent = 'stretch';
+  document.getElementById('container').style.alignContent = 'end';
 }
 onload = runRepaintTest;
 </script>
@@ -11,20 +11,20 @@ body {
   margin: 0;
 }
 #container {
-  display: flex;
-  align-content: space-around;
-  flex-flow: row wrap;
+  display: grid;
+  grid-auto-columns: 200px;
+  grid-auto-rows: auto;
+  grid-auto-flow: row;
+  align-content: start;
   width: 200px;
   height: 300px;
-  background-color: red;
+  background-color: orange;
 }
 .item {
   background-color: green;
-  border: solid thin blue;
-  width: 200px;
 }
 </style>
-<p style="height: 20px">Tests invalidation on align-content style change. Passes if there is no red.</p>
+<p style="height: 20px">Tests invalidation on align-content style change (position). Passes if the orange half is on the top.</p>
 <div id="container">
   <div class="item">
     <div style="height: 50px"></div>
@@ -32,4 +32,7 @@ body {
   <div class="item">
     <div style="height: 50px"></div>
   </div>
+  <div class="item">
+    <div style="height: 50px"></div>
+  </div>
 </div>