chore: remove hacks for IE8-, close: #7447 (#7512)

components/cascader/style/index.less

@@ -96,7 +96,6 @@
         transition: transform 0.2s ease;
       }
       &&-expand {
-        .ie-rotate(2);
         &:before {
           transform: rotate(180deg);
         }

components/checkbox/style/mixin.less

@@ -70,7 +70,7 @@
       left: 0;
       z-index: 1;
       cursor: pointer;
-      .opacity(0);
+      opacity: 0;
       top: 0;
       bottom: 0;
       right: 0;
@@ -168,23 +168,6 @@
       display: inline-block;
     }
   }
-
-  @ie8: \0screen;
-
-  // IE8 hack for https://github.com/ant-design/ant-design/issues/2148
-  @media @ie8 {
-    .@{checkbox-prefix-cls}-checked .@{checkbox-prefix-cls}-inner:before,
-    .@{checkbox-prefix-cls}-checked .@{checkbox-prefix-cls}-inner:after {
-      .iconfont-font("\e632");
-      font-weight: bold;
-      font-size: 8px;
-      border: 0;
-      color: #fff;
-      left: 2px;
-      top: 3px;
-      position: absolute;
-    }
-  }
 }
 
 @keyframes antCheckboxEffect {

components/menu/style/index.less

@@ -250,7 +250,6 @@
       position: absolute;
       content: "\e61d";
       right: 16px;
-      .ie-rotate(3);
       transform: rotate(270deg) scale(0.75);
     }
 
@@ -270,7 +269,6 @@
 
     &-open {
       &.@{menu-prefix-cls}-submenu-inline > .@{menu-prefix-cls}-submenu-title:after {
-        .ie-rotate(1);
         transform: rotate(180deg) scale(0.75);
       }
     }

components/radio/style/index.less

@@ -209,7 +209,7 @@ span.@{radio-prefix-cls} + * {
   .@{radio-prefix-cls}-inner,
   input[type="checkbox"],
   input[type="radio"] {
-    .opacity(0);
+    opacity: 0;
     width: 0;
     height: 0;
   }

components/select/style/index.less

@@ -359,7 +359,6 @@
 
   &-open {
     .@{select-prefix-cls}-arrow {
-      .ie-rotate(2);
       -ms-transform: rotate(180deg);
       &:before {
         transform: rotate(180deg);

components/spin/index.tsx

@@ -48,7 +48,7 @@ export default class Spin extends React.Component<SpinProps, any> {
 
   componentDidMount() {
     if (!isCssAnimationSupported()) {
-      // Show text in IE8/9
+      // Show text in IE9
       this.setState({
         notCssAnimationSupported: true,
       });

components/style/core/iconfont.less

@@ -4,8 +4,6 @@
   font-family: 'anticon';
   src: url('@{icon-url}.eot'); /* IE9*/
   src:
-  /* IE6-IE8 */
-  url('@{icon-url}.eot?#iefix') format('embedded-opentype'),
   /* chrome、firefox */
   url('@{icon-url}.woff') format('woff'),
   /* chrome、firefox、opera、Safari, Android, iOS 4.2+*/

components/style/mixins/compatibility.less

@@ -1,32 +1,5 @@
 // Compatibility for browsers.
 
-// rotate for ie8 and blow
-.ie-rotate(@rotation) {
-  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=@{rotation})";
-}
-
-// rotate for ie8 and blow
-// degrees unit
-.ie-rotate-via-degrees(@degrees) {
-  /* IE6-IE8 */
-  @radians: ~`parseInt("@{degrees}") * Math.PI * 2 / 360`;
-  @costheta: ~`Math.cos("@{radians}")`;
-  @sintheta: ~`Math.sin("@{radians}")`;
-  @negsintheta: ~`"@{sintheta}" * -1`;
-  -ms-filter: "progid:DXImageTransform.Microsoft.Matrix(sizingMethod='auto expand', M11=@{costheta}, M12=@{negsintheta}, M21=@{sintheta}, M22=@{costheta})";
-  zoom: 1;
-
-  :root & {
-    filter: none;
-  }
-}
-
-// support rotate for all browsers
-.cross-rotate(@degrees) {
-  .rotate(@degrees);
-  .ie-rotate-via-degrees(@degrees);
-}
-
 // Placeholder text
 .placeholder(@color: @input-placeholder-color) {
   // Firefox

components/style/mixins/iconfont.less

@@ -28,11 +28,10 @@
   display: inline-block;
   @font-scale: unit(@size / 12px);
   font-size: @font-size-base;
-  // ie8-9
+  // IE9
   font-size: ~"@{size} \9"; // lesshint duplicateProperty: false
   transform: scale(@font-scale) rotate(@rotate);
-  .ie-rotate-via-degrees(@rotate);
   :root & {
-    font-size: @font-size-base; // reset ie9 and above
+    font-size: @font-size-base; // reset IE9 and above
   }
 }

components/style/mixins/index.less

@@ -1,6 +1,5 @@
 // Mixins
 // --------------------------------------------------
-@import "opacity";
 @import "size";
 @import "compatibility";
 @import "clearfix";

components/style/mixins/opacity.less

@@ -1,8 +0,0 @@
-// Opacity
-
-.opacity(@opacity) {
-  opacity: @opacity;
-  // IE8 filter
-  @opacity-ie: (@opacity * 100);
-  filter: ~"alpha(opacity=@{opacity-ie})";
-}

components/tree-select/style/index.less

@@ -82,7 +82,6 @@
         }
         &.@{select-tree-prefix-cls}-switcher_close {
           .antTreeSwitcherIcon();
-          .ie-rotate(3);
           &:after {
             transform: rotate(270deg) scale(0.59);
           }

components/tree/style/index.less

@@ -107,7 +107,6 @@
         }
         &.@{tree-prefix-cls}-switcher_close {
           .antTreeSwitcherIcon();
-          .ie-rotate(3);
           &:after {
             transform: rotate(270deg) scale(0.59);
           }