I was able to do this with css. Add 'overflow: scroll' to 'body' and set a size for a div containing the 'canvas' element:

body {
    background-color: white;
    overflow: scroll;
}
#canvasdiv {
    width: 1200px;
    height: 900px;
    margin: 50px 0 0;
}
#canvas {
    width: auto !important;
    height: auto !important;
}