[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/col/index.vue

@@ -1,12 +1,10 @@
 <template>
   <div
-    :class="[`van-col`, { 
-      [`van-col-${span}`]: span,
-      [`van-col-offset-${offset}`]: offset,
-    }]"
+    class="van-col"
+    :class="{ [`van-col-${span}`]: span, [`van-col-offset-${offset}`]: offset}"
     :style="style"
   >
-      <slot></slot>
+    <slot></slot>
   </div>
 </template>