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

LayoutTests/fast/repaint/justify-items-change.html

Index: LayoutTests/fast/repaint/justify-items-change.html
diff --git a/LayoutTests/fast/repaint/justify-items-change.html b/LayoutTests/fast/repaint/justify-items-change.html
index 821ebec4373da4a4f7e74da0ef7599c29dde07f1..42b069c89c58f6e22edce02e4cc9a98ae33bcd56 100644
--- a/LayoutTests/fast/repaint/justify-items-change.html
+++ b/LayoutTests/fast/repaint/justify-items-change.html
@@ -12,32 +12,22 @@ body {
 }
 #container {
   display: grid;
-  grid: 100px 100px / 150px 150px;
+  grid: 200px / 300px;
   justify-items: end;
   width: 200px;
   height: 300px;
   background-color: red;
 }
-.item1 {
+.item {
   grid-row: 1;
   grid-column: 1;
   background-color: green;
-  border: solid thin blue;
   width: 50px;
 }
-.item2 {
-  grid-row: 1;
-  grid-column: 2;
-  background-color: green;
-  border: solid thin blue;
-  width: 50px;
 </style>
-<p style="height: 20px">Tests invalidation on justify-items style change. Passes if there is no red.</p>
+<p style="height: 20px">Tests invalidation on justify-items style change. Passes if green bar is left aligned.</p>
 <div id="container">
-  <div class="item1">
-    <div style="height: 50px"></div>
-  </div>
-  <div class="item2">
+  <div class="item">
     <div style="height: 50px"></div>
   </div>
 </div>