Prevent Chromium from wrongly taking the XRAY code-path in IFRAMEs
This is a modified commit of Giorgio M.
Test for xrayWindow.XPCNativeWrapper removed as xrayWindow.XPCNativeWrapper
is not available in Firefox92.
(xrayWindow.top !== unwrappedWindow.top) tested in Chromium and Firefox
with expected results both outside and inside iframes.