[improvement] Button: add round prop (#1885)

packages/button/demo/index.vue

@@ -31,13 +31,12 @@
 
     <demo-block :title="$t('title3')">
       <van-button loading />
-      <van-button loading type="primary" />
+      <van-button loading type="danger" />
     </demo-block>
 
     <demo-block :title="$t('title4')">
-      <van-button tag="a" href="https://www.youzan.com" target="_blank">
-        {{ $t('button') }}
-      </van-button>
+      <van-button type="danger" square>{{ $t('square') }}</van-button>
+      <van-button type="danger" round>{{ $t('round') }}</van-button>
     </demo-block>
   </demo-section>
 </template>
@@ -49,8 +48,7 @@ export default {
       title1: '按钮类型',
       title2: '按钮尺寸',
       title3: '加载状态',
-      title4: '自定义按钮标签',
-      title5: '页面底部操作按钮',
+      title4: '按钮形状',
       default: '默认按钮',
       primary: '主要按钮',
       danger: '危险按钮',
@@ -59,14 +57,15 @@ export default {
       normal: '普通按钮',
       small: '小型按钮',
       mini: '迷你按钮',
-      plain: '朴素按钮'
+      plain: '朴素按钮',
+      square: '方形按钮',
+      round: '圆形按钮'
     },
     'en-US': {
       title1: 'Type',
       title2: 'Size',
       title3: 'Loading',
-      title4: 'Custom Tag',
-      title5: 'Action Button',
+      title4: 'Shape',
       default: 'Default',
       primary: 'Primary',
       danger: 'Danger',
@@ -75,7 +74,9 @@ export default {
       normal: 'Normal',
       small: 'Small',
       mini: 'Mini',
-      plain: 'Plain'
+      plain: 'Plain',
+      square: 'Square',
+      round: 'Round'
     }
   }
 };