refactor: update select style (#3781)

Author: John60676

components/form/style/index.less

@@ -435,14 +435,14 @@ form {
 
   //select
   .@{ant-prefix}-select {
-    &-selection {
+    &-selector {
       border-color: @warning-color;
       &:hover {
         border-color: @warning-color;
       }
     }
-    &-open .@{ant-prefix}-select-selection,
-    &-focused .@{ant-prefix}-select-selection {
+    &-open .@{ant-prefix}-select-selector,
+    &-focused .@{ant-prefix}-select-selector {
       .active(@warning-color);
     }
   }

components/input/style/mixin.less

@@ -170,16 +170,16 @@
     .@{ant-prefix}-select {
       margin: -(@input-padding-vertical-base + 1px) (-@input-padding-horizontal-base);
 
-      .@{ant-prefix}-select-selection {
-        margin: -1px;
+      &.@{ant-prefix}-select-single:not(.@{ant-prefix}-select-customize-input)
+        .@{ant-prefix}-select-selector {
         background-color: inherit;
         border: @border-width-base @border-style-base transparent;
         box-shadow: none;
       }
 
       &-open,
       &-focused {
-        .@{ant-prefix}-select-selection {
+        .@{ant-prefix}-select-selector {
           color: @primary-color;
         }
       }
@@ -204,7 +204,7 @@
     border-bottom-right-radius: 0;
 
     // Reset Select's style in addon
-    .@{ant-prefix}-select .@{ant-prefix}-select-selection {
+    .@{ant-prefix}-select .@{ant-prefix}-select-selector {
       border-top-right-radius: 0;
       border-bottom-right-radius: 0;
     }
@@ -236,7 +236,7 @@
     border-bottom-left-radius: 0;
 
     // Reset Select's style in addon
-    .@{ant-prefix}-select .@{ant-prefix}-select-selection {
+    .@{ant-prefix}-select .@{ant-prefix}-select-selector {
       border-top-left-radius: 0;
       border-bottom-left-radius: 0;
     }
@@ -254,11 +254,11 @@
   }
 
   // Fix https://github.com/ant-design/ant-design/issues/5754
-  &-lg .@{ant-prefix}-select-selection--single {
+  &-lg .@{ant-prefix}-select-single .@{ant-prefix}-select-selector {
     height: @input-height-lg;
   }
 
-  &-sm .@{ant-prefix}-select-selection--single {
+  &-sm .@{ant-prefix}-select-single .@{ant-prefix}-select-selector {
     height: @input-height-sm;
   }
 
@@ -304,7 +304,7 @@
     }
 
     // reset border for Select, DatePicker, AutoComplete, Cascader, Mention, TimePicker, Input
-    & > .@{ant-prefix}-select > .@{ant-prefix}-select-selection,
+    & > .@{ant-prefix}-select > .@{ant-prefix}-select-selector,
     & > .@{ant-prefix}-calendar-picker .@{ant-prefix}-input,
     & > .@{ant-prefix}-select-auto-complete .@{ant-prefix}-input,
     & > .@{ant-prefix}-cascader-picker .@{ant-prefix}-input,
@@ -328,7 +328,7 @@
     }
 
     & > *:first-child,
-    & > .@{ant-prefix}-select:first-child > .@{ant-prefix}-select-selection,
+    & > .@{ant-prefix}-select:first-child > .@{ant-prefix}-select-selector,
     & > .@{ant-prefix}-calendar-picker:first-child .@{ant-prefix}-input,
     & > .@{ant-prefix}-select-auto-complete:first-child .@{ant-prefix}-input,
     & > .@{ant-prefix}-cascader-picker:first-child .@{ant-prefix}-input,
@@ -339,7 +339,7 @@
     }
 
     & > *:last-child,
-    & > .@{ant-prefix}-select:last-child > .@{ant-prefix}-select-selection,
+    & > .@{ant-prefix}-select:last-child > .@{ant-prefix}-select-selector,
     & > .@{ant-prefix}-calendar-picker:last-child .@{ant-prefix}-input,
     & > .@{ant-prefix}-select-auto-complete:last-child .@{ant-prefix}-input,
     & > .@{ant-prefix}-cascader-picker:last-child .@{ant-prefix}-input,