xception, null,
      "Unexpected exception thrown when setting up Range for simulated cloneContents()");
    assert_equals(typeof actualRange, "object",
      "typeof Range produced in actual iframe");
    assert_equals(typeof expectedRange, "object",
      "typeof Range produced in expected iframe");

    // NOTE: We could just assume that cloneContents() doesn't change
    // anything.  That would simplify these tests, taken in isolation.  But
    // once we've already set up the whole apparatus for extr