[Improvement] Progress: support gradient color (#1098)

docs/src/demo-common.js

@@ -33,6 +33,7 @@ Locale.add({
     red: '红色',
     orange: '橙色',
     yellow: '黄色',
+    purple: '紫色',
     tab: '标签',
     tag: '标签',
     desc: '描述信息',
@@ -60,6 +61,7 @@ Locale.add({
     red: 'Red',
     orange: 'Orange',
     yellow: 'Yellow',
+    purple: 'Purple',
     tab: 'Tab',
     tag: 'Tag',
     desc: 'Description',