Move WebGL 1 half_float_linear handling to command buffer.

BUG=570453
TEST=gpu_unittests, webgl_conformance
R=kbr@chromium.org,bajones@chromium.org,piman@chromium.org

Review URL: https://codereview.chromium.org/1665303002

Cr-Commit-Position: refs/heads/master@{#373977}
12 files changed