NNTP: Fix issue where dragged thumbnail had the wrong z-index.

BUG=20903

TEST=Drag a thumbnail and release the mouse where you drqagged the
thumbnail from. Now, be quick, and drag the same thumbnail again. THe
thumbnail should not be displayed behind any other thumbnails.


Review URL: http://codereview.chromium.org/203006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@25811 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/new_new_tab.js

@@ -872,8 +872,8 @@ function afterTransition(f) {
     // Make sure we do not use a timer during load since it slows down the UI.
     f();
   } else {
-    // The duration of all transitions are 500ms
-    window.setTimeout(f, 500);
+    // The duration of all transitions are .15s
+    window.setTimeout(f, 150);
   }
 }
 
@@ -1558,6 +1558,7 @@ var dnd = {
 
     item.style.left = x + 'px';
     item.style.top = y + 'px';
+    item.style.zIndex = 2;
   },
 
   // We listen to mousedown to get the relative position of the cursor for dnd.