[Improvement] optimize staticClass (#337)

* fix: Tabbar icon line-height

* [new feature] progress add showPivot prop

* [new feature] TabItem support vue-router

* [new feature] update document header style

* [Doc] add toast english ducoment

* [bugfix] Search box-sizing wrong

* [Doc] update vant-demo respo

* [Doc] translate theme & demo pages

* [Doc] add Internationalization document

* [bugfix] remove unnecessary props

* [fix] optimize clickoutside

* [new feature] optimize find-parent

* [new feature]: change document title accordinng to language

* [new feature] Pagination code review

* [improvement] adjust icon-font unicode

* [improvement] Icon spinner color inherit

* [improvement] icon default width

* [bugfix] DateTimePicker validate date props

* [bugfix] Tab item text ellipsis

* [improvement] optimize single line ellipsis

* [Improvement] optimzie staticClass

packages/radio/index.vue

@@ -2,21 +2,16 @@
   <div
     @click="handleRadioClick"
     class="van-radio"
-    :class="{
-      'van-radio--disabled': isDisabled
-    }">
+    :class="{ 'van-radio--disabled': isDisabled }">
     <span class="van-radio__input">
       <input
         :value="name"
         v-model="currentValue"
         type="radio"
         class="van-radio__control"
-        :disabled="isDisabled">
-      <span class="van-icon" :class="{
-        'van-icon-checked': currentValue === name,
-        'van-icon-check': currentValue !== name
-      }">
-      </span>
+        :disabled="isDisabled"
+      >
+      <van-icon :name="currentValue === name ? 'checked' : 'check'" />
     </span>
     <span class="van-radio__label" @click="handleLabelClick">
       <slot></slot>
@@ -25,11 +20,16 @@
 </template>
 
 <script>
+import Icon from '../icon';
 import findParent from '../mixins/find-parent';
 
 export default {
   name: 'van-radio',
 
+  components: {
+    [Icon.name]: Icon
+  },
+
   mixins: [findParent],
 
   props: {