[8u20] RFR: JDK-8041791,String.toLowerCase regression - violates Unicode standard

[Naoto Sato]

Hello,

Please review the following changes for the subject bug 
(https://bugs.openjdk.java.net/browse/JDK-8041791) to the 8u repository:

http://cr.openjdk.java.net/~naoto/8041791/jdk8u-dev/webrev.00/

It's basically the same change to the JDK9 line, just resolving the 
conflict with the fix to 8032012.

Naoto