[13] RFR (S): 8218758: [TESTBUG] compiler/cha/StrengthReduceInterfaceCall.java misses recompilation event

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/8218758/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8218758

The test checks that nmethod has been invalidated by ensuring there's no 
nmethod installed at the moment. But it's not robust enough: it is 
possible that JVM initiates compilation before the check happens.

The fix is to harden the logic to additionaly check that if there's 
nmethod installed it differs from the one observed earlier.

Testing: hs-precheckin-comp, tier1-5

Best regards,
Vladimir Ivanov