Fix DAG connectivity for morphology filter

When processing a morphology filter on the GPU, pass the processed texture, not the original source texture.  This doesn't affect Chrome, since it doesn't use the skia filter DAG yet.

(I probably broke this in r5241, and it would've been caught by gm/imagefiltersgraph.cpp, but we don't have any baselines for it.  :/)

[robertphillips, 2012-10-02 00:24:30]

LGTM

[Stephen White, 2012-10-03 16:50:10]

On 2012/10/02 00:24:30, robertphillips wrote:
> LGTM

Landed as https://code.google.com/p/skia/source/detail?r=5766.  Closing.