WebGLRenderingContext: Add more GLenum validation checks.

Adding validation checks for cullFace, depthFunc, frontFace.

BUG=266296
R=kbr@chromium.org, zmo@chromium.org

Review URL: https://chromiumcodereview.appspot.com/21199004

git-svn-id: svn://svn.chromium.org/blink/trunk@155342 bbb929c8-8fbe-4397-9dbb-9b2b20218538