glEnumToString = function (gl, value) {
  for (var p in gl) {
    if (gl[p] === value) {
      return p;
    }
  }
  return '0x' + value.toString(16);
}
Converts a WebGL enum to a string
@param {!WebGLContext} gl The WebGLContext to use.
@param {number} value The enum value.
@return {string} The enum as a string.