RFR (XS): 8162815: unnecessary object creation in reflection

[Claes Redestad]

Hi,

I'd like to sponsor this bug fix provided by Tomáš Hůrka to remove a new 
and dup left behind in generated accessor methods after moving these to 
use appropriate valueOf methods for boxing primitive returns.

Bug: https://bugs.openjdk.java.net/browse/JDK-8162815
Webrev: http://cr.openjdk.java.net/~redestad/8162815/webrev.01/

This appears to have a very limited effect to peak performance in 
HotSpot (interpreter and C1 level code seem to hurt a bit), but should 
be fixed for correctness.

Thanks!

/Claes