Add BlendComposite.java

The class is adapted from a demo tool for Blending Modes written by
Romain Guy (romainguy@android.com). The tool is available at
http://www.curious-creature.org/2006/09/20/new-blendings-modes-for-java2d/

Change-Id: I8f7c7ca08d3078106056764a4e2f1ce95d990137
Optimize Blend composites.

Removed redundant array allocations to improve performance for various
blending modes.

Change-Id: Iaba1d6ff3ad03eebdc859c599b610cc593370438