[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/field/index.vue

@@ -2,7 +2,8 @@
   <van-cell
     :title="label"
     :required="required"
-    :class="['van-field', {
+    class="van-field"
+    :class="{
       'van-field--has-textarea': type === 'textarea',
       'van-field--nolabel': !label,
       'van-field--disabled': $attrs.disabled,
@@ -11,7 +12,7 @@
       'van-field--autosize': autosize,
       'van-field--has-icon': hasIcon,
       'van-hairline--surround': border
-    }]">
+    }">
     <textarea
       v-if="type === 'textarea'"
       v-bind="$attrs"