Fix incorrectly optimized out live range

For x ? y : z style structures, the live range starts at z, but
may also hold the value of y. Make sure that the refcounting check
takes this

Fix incorrectly optimized out live range

For x ? y : z style structures, the live range starts at z, but
may also hold the value of y. Make sure that the refcounting check
takes this into account, by checking the type of a potential phi
user.

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