RFR(XS): 8242502: UnexpectedDeoptimizationTest.java failed "assert(phase->type(obj)->isa_oopptr()) failed: only for oop input"

[Roland Westrelin]

https://bugs.openjdk.java.net/browse/JDK-8242502
http://cr.openjdk.java.net/~roland/8242502/webrev.00/

I wasn't able to reproduce that failure (neither by running the test or
with the replay file) but I suspect the assert fails because it
encounters a unexpected top node.

Roland.