function addVertexArrayObjectSupport(gl) {
    if (!gl || !defaults.enableVertexArrayObjects) {
      return;
    }
    if (utils.isWebGL1(gl)) {
      var ext = gl.getExtension("OES_vertex_array_object");
      if (ext) {
        gl.createVertexArray = function() {
          return ext.createVertexArrayOES();
        };
        gl.deleteVertexArray = function(v) {
          ext.deleteVertexArrayOES(v);
        };
        gl.isVertexArray = function(v) {
          return ext.isVertexArrayOES(v);
        };
        gl.bindVertexArray = function(v) {
          ext.bindVertexArrayOES(v);
        };
        gl.VERTEX_ARRAY_BINDING = ext.VERTEX_ARRAY_BINDING_OES;
      }
    }
  }
Adds Vertex Array Objects to WebGL 1 GL contexts if available
@param {WebGLRenderingContext} gl A WebGLRenderingContext