fix several dumb bugs in GrInOrderDrawBuffer

[bsalomon, 2012-03-08 16:00:17]

This code has only had limited testing before now. I have a patch in development
that would draw all paths through the GrInOrderDrawBuffer. I found several bugs
that are fixed by this patch.

One that might require some explanation is in drawRect. drawRect is overloaded
in GrIODB so that it can attempt to concatenate rect draws into a single larger
draw. Part of that optimization is moving all the rects to device space so that
view matrix changes don't force separate draws. When the samplers are configured
to use vertex positions as input coordinates then their matrices have to be
modified to account for the coordinate change. The AutoDeviceCoordDraw handles
this.

This may argue for GrIODB inserting explicit texture coords because sampler
matrix changes will also force separate draws, but I'll leave that for another
change.

[TomH, 2012-03-08 16:30:27]

LGTM

[bsalomon, 2012-03-08 16:42:06]

Closed with r3342.