support missing values in line chart

If a value is not defined for a line, the graph will be correctly displayed !

Sample data that will show a good result : 

var mydata1 = {
	labels : ["January","February","March","April","May","June","July"],
	datasets : [
		{
			fillColor : "rgba(220,220,220,0.5)",
			strokeColor : "rgba(220,220,220,1)",
			pointColor : "rgba(220,220,220,1)",
			pointStrokeColor : "#fff",
			data : [0.65,0.59,0.90,0.81,0.56,0.55,1.00],
      title : "pFirst data"
		},
		{
			fillColor : "rgba(151,187,205,0.5)",
			strokeColor : "rgba(151,187,205,1)",
			pointColor : "rgba(151,187,205,1)",
			pointStrokeColor : "#fff",
			data : [,0.34,,0.19,0.96,0.27,],
      title : "pSecond data"
		}
	]
}