remove unused button style, fix #1293

style/mixins/button.less

@@ -83,10 +83,6 @@
   .button-size(@btn-padding-base; @font-size-base; @border-radius-base);
   .user-select(none);
   .transition(all .3s @ease-in-out);
-  transform: translate3d(0, 0, 0);
-  // Fix for ie8 border-radius
-  // http://css3pie.com/documentation/known-issues/#z-index
-  position: relative\0;
 
   > .@{iconfont-css-prefix} {
     line-height: 1;