Bug 746176 - bounds/test_zoom.html fails on OS X, disable whole file for now

accessible/tests/mochitest/bounds/test_zoom.html

@@ -22,6 +22,14 @@
   <script type="application/javascript">
     function doTest()
     {
+      // Bug 746176: Failure of this whole test file on OS X.
+      if (MAC) {
+        todo(false, "Fix bug 746176 on Mac");
+        closeBrowserWindow();
+        SimpleTest.finish();
+        return;
+      }
+
       var tabDocument = currentTabDocument();
       var p1 = tabDocument.getElementById("p1");
       var p2 = tabDocument.getElementById("p2");