In very rare cases optimizations in IfNode::Ideal() and Loopopts may incorrectly change control of a type node
because TypeNode::depends_only_on_test() returns true.

The next code

if (a != b)
  if (a != null && b != null)
    if (a != b)
      x = ((CastClass)a).f;

is transformed into

if (a != b)
  x = ((CastClass)a).f;