function destroyVBOs(geo) {
        if (document.getElementById(geo.canvas.canvasId)) { // Context won't exist if canvas has disappeared
            if (geo.vertexBuf) {
                geo.vertexBuf.destroy();
            }
            if (geo.normalBuf) {
                geo.normalBuf.destroy();
            }
            if (geo.indexBuf) {
                geo.indexBuf.destroy();
            }
            if (geo.uvBuf) {
                geo.uvBuf.destroy();
            }
            if (geo.uvBuf2) {
                geo.uvBuf2.destroy();
            }
            if (geo.colorBuf) {
                geo.colorBuf.destroy();
            }
        }
    }
Backend that tracks statistics on loading states of nodes during scene traversal.

This supports the "loading-status" events that we can listen for on scene nodes.

When a node with that listener is pre-visited, it will call getStatus on this module to
save a copy of the status. Then when it is post-visited, it will call diffStatus on this
module to find the status for its sub-nodes, which it then reports through the "loading-status" event.

@private