[8u40] Request for approval: 8035974 Refactor DigestBase.engineUpdate() method for better code generation by JIT compiler

[Vladimir Kozlov]

Requesting approval for the backport of JDK-8035974. The change was 
pushed to jdk 9 in May and it is applied cleanly to jdk8u sources:

Main RFE:  https://bugs.openjdk.java.net/browse/JDK-8035974
Changeset: http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/dabb44358772
Review: 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-May/026945.html

Corresponding Hotspot changes (8035968+8035974) will be pushed through 
jdk8u/hs-dev as usual.

Thanks,
Vladimir