fix position set not trigger dirty
fix position set not trigger dirty

chenfwind/echarts,chenfwind/echarts,hexj/echarts,apache/incubator-echarts,ecomfe/echarts,starlkj/echarts,apache/incubator-echarts,100star/echarts,ecomfe/echarts,100star/echarts,hexj/echarts,hexj/echarts,starlkj/echarts,starlkj/echarts