[improvement] optimize wxml (#858)

example/pages/radio/index.wxml

@@ -1,12 +1,23 @@
-<demo-block title="基本用法">
-  <van-radio-group value="{{ radio1 }}" data-key="radio1" bind:change="onChange" custom-class="demo-radio-group">
+<demo-block title="基本用法" padding>
+  <van-radio-group
+    value="{{ radio1 }}"
+    data-key="radio1"
+    custom-class="demo-radio-group"
+    bind:change="onChange"
+  >
     <van-radio name="1" custom-class="demo-radio">单选框 1</van-radio>
     <van-radio name="2" custom-class="demo-radio">单选框 2</van-radio>
   </van-radio-group>
 </demo-block>
 
-<demo-block title="禁用状态">
-  <van-radio-group value="{{ radio2 }}" data-key="radio2" bind:change="onChange" disabled custom-class="demo-radio-group">
+<demo-block title="禁用状态" padding>
+  <van-radio-group
+    disabled
+    value="{{ radio2 }}"
+    data-key="radio2"
+    custom-class="demo-radio-group"
+    bind:change="onChange"
+  >
     <van-radio name="1" custom-class="demo-radio">单选框 1</van-radio>
     <van-radio name="2" custom-class="demo-radio">单选框 2</van-radio>
   </van-radio-group>

packages/checkbox-group/index.wxml

@@ -1,3 +1 @@
-<view class="custom-class">
 <slot />
-</view>

packages/radio-group/index.wxml

@@ -1,3 +1 @@
-<view class="custom-class">
 <slot />
-</view>

packages/search/index.wxml

@@ -2,7 +2,6 @@
   class="van-search custom-class {{ showAction || useActionSlot ? 'van-search--show-action' : '' }}"
   style="background: {{ background }}"
 >
-  <view class="van-search__field">
   <van-field
     clearable
     type="search"
@@ -11,6 +10,7 @@
     error="{{ error }}"
     border="{{ false }}"
     confirm-type="search"
+    class="van-search__field"
     value="{{ value }}"
     disabled="{{ disabled }}"
     readonly="{{ readony }}"
@@ -24,7 +24,6 @@
     bind:change="onChange"
     bind:confirm="onSearch"
   />
-  </view>
   <view wx:if="{{ showAction || useActionSlot }}" class="van-search__action">
     <slot wx:if="{{ useActionSlot }}" name="action" />
     <view wx:else bind:tap="onCancel" class="cancel-class">取消</view>

packages/tabbar-item/index.wxml

@@ -5,12 +5,8 @@
   <view class="van-tabbar-item__icon {{ dot ? 'van-tabbar-item__icon--dot' : '' }}">
     <van-icon wx:if="{{ icon }}" name="{{ icon }}" info="{{ info }}" />
     <block wx:else>
-      <block wx:if="{{ active }}">
-        <slot name="icon-active" />
-      </block>
-      <block wx:else>
-        <slot name="icon" />
-      </block>
+      <slot wx:if="{{ active }}" name="icon-active" />
+      <slot wx:else name="icon" />
       <view wx:if="{{ info !== null }}" class="van-icon__info">{{ info }}</view>
     </block>
   </view>