Only use sized format on IMG/ES3 for single channel.

BUG=skia:2922

Review URL: https://codereview.chromium.org/638293004
Rebaseline mixedxfermodes on ubuntu/nvprmsaa4

TBR=

Review URL: https://codereview.chromium.org/657603005
Ignore ubuntu nvprmsaa4/mixed_xfermodes GM result.

BUG=skia:2443

Review URL: https://codereview.chromium.org/653153003
Changed "Profile" to "Cube" in ColorCube

A few references to "profile" still existed in SkColorCubeFilter, so I removed them.

BUG=skia:

Review URL: https://codereview.chromium.org/651303002