RFR 8235238: Parsing a time string ignores any custom TimeZoneNameProvider

[naoto.sato at oracle.com]

Hi,

Please review the fix for the following issue:

https://bugs.openjdk.java.net/browse/JDK-8235238

The proposed changeset is located at:

https://cr.openjdk.java.net/~naoto/8235238/webrev.00/

The fix will retrieve the custom zone names from the time zone name 
provider, for the custom ZoneRulesProvider implementations.

Naoto