Fix LinkHighlight to position correctly w.r.t. squashed layers.

LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html

Index: LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html
diff --git a/LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html b/LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html
index 9985e802d7f445dfca94b9158cfdb39b2a5b5319..f57a93fd348638942fbeaccbdf2c555d72fb6a8e 100644
--- a/LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html
+++ b/LayoutTests/compositing/gestures/gesture-tapHighlight-with-squashing.html
@@ -29,15 +29,21 @@
     background-color: orange;
   }
 
+  .squash-spacer {
+    position: relative;
+    top: 40px;
+  }
+
   .target {
     position: relative;
     top: 80px;
+    height: 10px; width: 100%;
   }
 </style>
 
 <script>
   if (window.testRunner) {
-    testRunner.dumpAsText();
+    testRunner.dumpAsTextWithPixelResults();
     testRunner.waitUntilDone();
   }
 
@@ -53,7 +59,7 @@
 
     if (window.eventSender) {
       eventSender.gestureShowPress(x, y);
-      window.testRunner.notifyDone();
+      window.setTimeout(function() { window.testRunner.notifyDone(); }, 0);
     }
   }
 
@@ -64,6 +70,7 @@
   <div class='fixed composited'></div>
   <div class='container'>
     <div class='composited'></div>
+    <div class='squash-spacer'></div>
     <div class='target'>
       <a href='#' id='targetLink'>Target Link.</a>
     </div>