Fix lighting filters vs. flipY

There were three different problems with lighting filters:

1)  Texture offsets (fImageIncrement) have to be signed depending on whether the texture is "right way up" (texture upload) or "upside down" (render target), so the surface normals were coming out upside down.
2)  Light normals have to y-negated on upload
These two bugs were cancelling each other out in SampleApp, (where we were testing w/textures) but not in Chrome (where we were testing w/render targets).
3)  The extract-the-height-from-the-view-matrix hack I was using to compare light positions vs. gl_FragCoord doesn't work in Chrome where we compile with GR_STATIC_RECT_VB, and the view matrix contains more than the viewport transform (to accomodate the canonical vertex buffer).  Fixed by passing the destination render target to GrGLProgramStage::setData(), so it can flip the light positions in Y on the CPU.

[bsalomon, 2012-07-13 18:16:06]

LGTM

[TomH, 2012-07-13 18:21:23]

LGTM

[Stephen White, 2012-07-16 15:42:11]

On 2012/07/13 18:21:23, TomH wrote:
> LGTM

Landed as http://code.google.com/p/skia/source/detail?r=4605; closing.