update button cirle outline style

style/components/button.less

@@ -46,10 +46,6 @@
     .btn-circle(@btn-prefix-cls);
   }
 
-  &-circle-outline {
-    .btn-circle-outline;
-  }
-
   &:after {
     font-family: anticon;
     content: "\e6a1";

style/mixins/button.less

@@ -192,50 +192,6 @@
   }
 }
 
-// circle button with stroke border
-.btn-circle-outline() {
-  position: relative;
-
-  &:not([disabled]):before {
-    position: absolute;
-    top: 0;
-    left: 0;
-    right: 0;
-    bottom: 0;
-    display: inline-block;
-    .opacity(0);
-    border-radius: 50% 50%;
-    content: " ";
-    .scale(0, 0);
-    .transition(all .3s @ease-in-out);
-    z-index: 0;
-    background-color: @primary-color;
-  }
-
-  &:not([disabled]):hover,
-  &:not([disabled]):focus,
-  &:not([disabled]):active,
-  &:not([disabled]).active {
-    > .@{iconfont-css-prefix} {
-      color: @btn-primary-color;
-      position: relative;
-    }
-  }
-
-  &:not([disabled]):hover:before,
-  &:not([disabled]):focus:before,
-  &:not([disabled]):active:before,
-  &:not([disabled]).active:before {
-    .opacity(1);
-    .scale(1, 1);
-  }
-
-  &:not([disabled]):active:before,
-  &:not([disabled]).active:before {
-    background-color: tint(@primary-color, 20%);
-  }
-}
-
 // Horizontal button groups styl
 // --------------------------------------------------
 .btn-group(@btnClassName: btn) {