De-flake only-valid-drop-targets-receive-file-drop.

LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html

Index: LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html
diff --git a/LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html b/LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html
index 0ef77a214e959e2ae284c3ddb91fd82e6a6b8f62..13b4252c8d24b52d96c2e372dabef1138a3f15b5 100644
--- a/LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html
+++ b/LayoutTests/fast/events/only-valid-drop-targets-receive-file-drop.html
@@ -8,6 +8,7 @@ div, span {
 </style>
 <script>
 var dropReceived;
+var beforeUnloadReceived = false;
 function log(str)
 {
     var result = document.getElementById('result');
@@ -57,16 +58,17 @@ window.onload = function()
     window.addEventListener('beforeunload', function (e) {
         if (!dropReceived)
             log('Drop not received');
+        beforeUnloadReceived = true;
         e.preventDefault();
         testRunner.notifyDone();
     });
 
     dragDrop(drop1);
-    unloadExpected = true;
     dragDrop(drop2);
     window.setTimeout(function () {
         // Deadman's switch to fail quickly.
-        log('FAIL: navigation expected');
+        if (!beforeUnloadReceived)
+            log('FAIL: navigation expected');
         testRunner.notifyDone();
     }, 0);
 }