RFR 8/9: 8068278 ArrayIndexOutOfBoundsException instead of DateTimeException in j.t.chrono.JapaneseChronology.eraOf()

[Roger Riggs]

Please review this correction of a JapaneseEra range check in java.time.
The error was discovered during development of additional conformance 
tests (to be delivered separately).

Webrev:
   http://cr.openjdk.java.net/~rriggs//webrev-era-8068278

Issue:
<https://bugs.openjdk.java.net/browse/JDK-8068278> 8068278 
ArrayIndexOutOfBoundsException instead of DateTimeException in 
j.t.chrono.JapaneseChronology.eraOf()

Thanks, Roger