Consolidate read/write funcs in context. Remove support for reading pixels from a surface that's not a target. It's currently broken and neither used nor tested. Review URL: https://codereview.chromium.org/648863002
This is VERY preliminary, but it was sufficient for me to get 32 bit floating point textures in a sample app BUG=skia: R=bsalomon@chromium.org, bsalomon@google.com Author: joshualitt@chromium.org Review URL: https://codereview.chromium.org/359803003