css3 自动无限缩放

@-webkit-keyframes scaleDraw {
                0% {
                    -webkit-transform:scale(1);
                }
                25% {
                    -webkit-transform:scale(1.1);
                }
                50% {
                    -webkit-transform:scale(1);
                }
                75% {
                    -webkit-transform:scale(1.1);
                }
            }
            #drawCon1{
                -webkit-animation-name: scaleDraw;
                -webkit-animation-timing-function: ease-in-out;
                -webkit-animation-iteration-count: infinite;
                -webkit-animation-duration: 8s;
                -webkit-animation-direction: alternate;
            }