[OpenJDK 2D-Dev] Review request for http://cr.openjdk.java.net/~ceisserer/fix10/

[Clemens Eisserer]

Hi,

Please review my fix at http://cr.openjdk.java.net/~ceisserer/fix10/
I haven't created a an official bug-id, because due to the migration
to JIRA those user reports don't seem to be directly useable anyway.

Problem description:
For transformed blits the xrender pipeline uses caching-logic to be
able to use the same mask again when geometry doesn't change.
However, that logic didn't take into account changes of the "extra alpha" value.

Fix description:
The pipeline now also stores and validates against the extra-alpha
value which was used the last time the mask was prepared.

Also available is a small regression test, please feel free to modify
or discard it.

Thanks, Clemens