function getCanvas(canvas, name){
      if(!canvas){
        canvas = D.create('canvas');
        if (typeof FlashCanvas != "undefined" && typeof canvas.getContext === 'function') {
          FlashCanvas.initElement(canvas);
        }
        canvas.className = 'flotr-'+name;
        canvas.style.cssText = 'position:absolute;left:0px;top:0px;';
        D.insert(el, canvas);
      }
      _.each(size, function(size, attribute){
        D.show(canvas);
        if (name == 'canvas' && canvas.getAttribute(attribute) === size) {
          return;
        }
        canvas.setAttribute(attribute, size * o.resolution);
        canvas.style[attribute] = size + 'px';
      });
      canvas.context_ = null; // Reset the ExCanvas context
      return canvas;
    }
Initializes the canvas and it's overlay canvas element. When the browser is IE, this makes use
of excanvas. The overlay canvas is inserted for displaying interactions. After the canvas elements
are created, the elements are inserted into the container element.