setBlendMode = function (srcBlend, dstBlend)
        {
            if (srcBlend !== this.srcBlend || dstBlend !== this.dstBlend)
            {
                var gl = this.context.gl;

                this.srcBlend = srcBlend;
                this.dstBlend = dstBlend;

                if (this.isDrawing)
                {
                    this.flush();
                    gl.blendFunc(this.srcBlend, this.dstBlend);
                }
            }
        }
Internal boot handler for the WebGL Renderer.

@method SpinePlugin#bootWebGL
@private
@since 3.19.0