<i18n dev> RFR :8023563: Bottleneck in java.util.TimeZone.getDefaultInAppContext

[Seán Coffey]

Performance regression reported where a high number of threads calling 
TimeZone.getDefault can run into a bottleneck on AppContext accessor 
calls. The bug ID is 8023563 but it's not visible on bugs.sun.com yet.

Turns out that we're unnecessarily going through the AppContext in 
certain scenarios. Main aim is to use AppContext when using applets. We 
should check for presence of security manager (along with loading for 
AppContext class) in such cases.

http://cr.openjdk.java.net/~coffeys/webrev.8023563/webrev/

This fix is not applicable to jdk8 as new code is currently being worked 
on there which eliminates AppContext use.

Regards,
Sean.