Doc: update component document && examples

packages/cell/index.vue

@@ -2,7 +2,7 @@
   <a :class="['van-cell', { 'van-cell--required': required }]" :href="url" @click="$emit('click')">
     <div
       class="van-cell__title"
-      v-if="this.$slots.title || title"
+      v-if="$slots.title || title"
     >
       <slot name="icon">
         <i v-if="icon" class="van-icon" :class="'van-icon-' + icon"></i>
@@ -14,10 +14,10 @@
     </div>
     <div
       class="van-cell__value"
-      v-if="value || this.$slots.default"
+      v-if="value || $slots.default"
       :class="{
         'van-cell__value--link': isLink,
-        'van-cell__value--alone': !this.$slots.title && !title && !label
+        'van-cell__value--alone': !$slots.title && !title && !label
       }"
     >
       <slot>

packages/panel/index.vue

@@ -10,7 +10,7 @@
     <div class="van-panel__content">
       <slot></slot>
     </div>
-    <div class="van-panel__footer" v-if="this.$slots.footer">
+    <div class="van-panel__footer" v-if="$slots.footer">
       <slot name="footer"></slot>
     </div>
   </div>

packages/vant-css/src/badge.css

@@ -32,9 +32,7 @@
       display: block;
     }
     &::after {
-      @mixin border-retina (top);
-      @mixin border-retina (right);
-      @mixin border-retina (left);
+      @mixin border-retina (top, right, left);
     }
   }
 

packages/vant-css/src/cell.css

@@ -37,6 +37,10 @@
 
   &__title {
     display: table-cell;
+
+    .van-icon {
+      margin-right: 5px;
+    }
   }
 
   &__label {

packages/vant-css/src/loading.css

@@ -11,6 +11,7 @@
 
 .van-loading {
   font-size: 0;
+  line-height: 0;
 
   &--circle {
     width: 16px;