[8u] Request for approval of backport from jdk9 : 8048583: CustomMediaSizeName class matching to standard media is too loose

[Phil Race]

Bug: https://bugs.openjdk.java.net/browse/JDK-8048583
Review thread : 
http://mail.openjdk.java.net/pipermail/2d-dev/2014-July/004690.html
JDK 9 fix : http://hg.openjdk.java.net/jdk9/client/jdk/rev/b03d9329401f
Identical JDK 8 fix : http://cr.openjdk.java.net/~prr/8048583.8u/

-phil