vuejs2

Describe the bug
When createUploaderComponent has been created, emits specification only described the usage as an array (eg. ['update:label', 'change']), later on they added the ability to provide an object for stricter type checking and validation, very much like props.
Currently createUploaderComponent only supports emits as an array and props as an object

**Codepen/jsFid

Svg supported ie10+ and it should be default choice.

1、能否设置图片分辨率尺寸。
2、添加图片或替换图片时，是否可以固定长宽比自动缩放。

I feel like indexOf's optional second parameter: fromIndex, is an unsung hero.

It has saved me many times from having to slice an array before calling indexOf.

Would you consider a PR with an example using fromIndex?