RFR 8160312: ArrayIndexOutOfBoundsException when comparing strings case insensitive

[Xueming Shen]

Hi,

Please help codereview the change for JDK-8160312.

issue: https://bugs.openjdk.java.net/browse/JDK-8160312
webrev: http://cr.openjdk.java.net/~sherman/8160312/webrev

This a regression caused by fix for JDK-8151384,

http://cr.openjdk.java.net/~chegar/8151384/webrev.02

in which it over-optimizes "if (c1 != c2) ..." path to invoke
CharacterDataLatin1 method directly, based on the incorrect
assumption that the upper case of a latin1 character is a latin1
character. The "general" Character.toLowerCase() should be used
here instead.

Thanks,
Sherman