Fix image name typo in ImageTest

Change-Id: Ia1d65d2c1e69bbc6301e3d15c8315b336af3f021
diff --git a/user/test/com/google/gwt/user/client/ui/ImageTest.java b/user/test/com/google/gwt/user/client/ui/ImageTest.java
index b1717a2..6ee5dd3 100644
--- a/user/test/com/google/gwt/user/client/ui/ImageTest.java
+++ b/user/test/com/google/gwt/user/client/ui/ImageTest.java
@@ -783,7 +783,7 @@
   public void testWrapOfSubclass() {
     String uid = Document.get().createUniqueId();
     DivElement div = Document.get().createDivElement();
-    div.setInnerHTML("<img id='" + uid + "' src='counting-forward.png'>");
+    div.setInnerHTML("<img id='" + uid + "' src='counting-forwards.png'>");
     Document.get().getBody().appendChild(div);
 
     final TestImage image = TestImage.wrap(Document.get().getElementById(uid));