disable osx tests part 2 test_caretmoved.xul had conflicts

accessible/tests/mochitest/events/test_caretmove.xul

@@ -28,6 +28,13 @@
 
     function doTests()
     {
+
+      if (MAC) {
+        todo(false, "Make these tests pass on OSX (bug 650294)");
+        SimpleTest.finish();
+        return;
+      }
+
       gQueue = new eventQueue(EVENT_TEXT_CARET_MOVED);
 
       var id = "textbox";