static _bucketFor(sizePower, pixelType) {
        if (!Number.isInteger(sizePower) || sizePower < 0 || sizePower > 50) {
            throw new DetailedError("Bad sizePower", {sizePower, pixelType});
        }

        let pool = pixelType === WebGLRenderingContext.FLOAT ? FLOAT_POOL : BYTE_POOL;
        while (pool.length <= sizePower) {
            pool.push([])
        }
        return pool[sizePower];
    }
@param {!int} sizePower
@param {!int} pixelType
@returns {!Array.<!WglTexture>}
@private