This fix foes not implement getRater() in ogl surfaces.
Instead, it provides a blit for custom composite, which
prepares a snapshot of the destination surface (which
is one of ogl surfaces) and delegates the work to the
general blit, which now extracts raster from the snapshot.
A result of general blit's work is transferred to the original
Changes in OGLSurfaceDataProcy is required in order to prevent
getting an accelerated copy of original source image as an
operand of the blit. Now we first check for composite type,
and only then (if composite is not specified, or is a kind
of alpha composite) we take into account other conditions.
So this fix does not change anything for the case of alpha composites
but affects only XOR and custom composites case.
Suggested fix: http://sa.us.oracle.com/projects/java2d_data/7u10/7124347/