No need to detect change in size when opting for PositionedMovementLayout

LayoutTests/fast/block/positioning/positioned-movement-layout-when-height-changes.html

Index: LayoutTests/fast/block/positioning/positioned-movement-layout-when-height-changes.html
diff --git a/LayoutTests/fast/block/positioning/positioned-movement-layout-when-width-changes.html b/LayoutTests/fast/block/positioning/positioned-movement-layout-when-height-changes.html
similarity index 76%
copy from LayoutTests/fast/block/positioning/positioned-movement-layout-when-width-changes.html
copy to LayoutTests/fast/block/positioning/positioned-movement-layout-when-height-changes.html
index 0db94ca2c19a331c6d35e6eeecbde470a5abcbee..1fb9865f877e930d4b56d69ee9b7ee970254570b 100644
--- a/LayoutTests/fast/block/positioning/positioned-movement-layout-when-width-changes.html
+++ b/LayoutTests/fast/block/positioning/positioned-movement-layout-when-height-changes.html
@@ -3,11 +3,6 @@
     body {
         margin: 0;
     }
-    #top {
-        position: relative;
-        height: 500px;
-        width: 500px;
-    }
     #container {
         position: absolute;
         top: 0px;
@@ -19,9 +14,9 @@
     #test {
         position: absolute;
         top: 0px;
-        bottom: 0px;
-        left: 0px;
-        right: 140px;
+        bottom: 500px;
+        left: 140px;
+        right: 540px;
         overflow: hidden;
     }
     .contents {
@@ -47,7 +42,6 @@
     function runTest()
     {
         test = document.getElementById("test");
-        test.style['margin-left'] = '100%';
         addChildren(test);
 
         for (i = 0; i < 20; i++) {
@@ -59,7 +53,7 @@
         addChildren(test);
         document.body.offsetTop;
 
-        test.style['margin-left'] = 'initial';
+        test.style['top'] = '300px';
     }
     window.onload = runTest;
 </script>
@@ -68,4 +62,4 @@
     <div id="test"></div>
 </div>
 </div>
-crbug.com/426166: Tests positioned movement layout when it needs to layout children because it's width has changed.
+Tests positioned movement layout when its height has changed.