Use rounding to 8888 in lighting filters, raster path.

Use rounding to 8888 in lighting filters, raster path.

when converting float -> 8-bit BGRA in lighting filters, use rounding
rather than floor(). This makes the GPU and raster paths match more
closely (as tested by Blink test
feDiffuseLighting-linearrgb-lighting-color.svg).

Will affect the LSB of lighting, imagefiltersscaled GMs.

R=junov@chromium.org
BUG=skia:

Review URL: https://codereview.chromium.org/205073002

git-svn-id: http://skia.googlecode.com/svn/trunk@13863 2bbb7eff-a529-9590-31e7-b0007b416f81