Update misc.coffee to handle tooltip exception
Update misc.coffee to handle tooltip exception

to handle exception thrown when tooltip mode is chosen to be "NONE" and mouse is hovered over the svg elements.

chaosmail/line-chart,pacozaa/line-chart,pacozaa/line-chart,pacozaa/line-chart,chaosmail/line-chart,n3-charts/line-chart-vanilla,n3-charts/line-chart-vanilla,n3-charts/line-chart,chaosmail/line-chart,pacozaa/line-chart,n3-charts/line-chart,chaosmail/line-chart,n3-charts/line-chart-vanilla,n3-charts/line-chart,n3-charts/line-chart,chaosmail/line-chart,pacozaa/line-chart,n3-charts/line-chart-vanilla