If a table has heigth and last column is auto width
let width = ''
// is_last_column, true && top_always_true && height_set_by_user, true
if ( this.columns.length === index + 1 && top && this.$parent.bodyHeight !== 0) {
// width will be 0 + this.$parent.scrollBarWidth === this.$parent.scrollBarWidth
// so last column will be 10~20px(the width of scrollBar)
}
there is an example with iview@2.8.0
[gist](https://gist.github.com/anonymous/e04e86c9e99d4d1e97bf327769acd345)
[demo on jsbin](http://jsbin.com/soqogagiqu)
