fix <component> init error

[xlshen]

Warning: The tag is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

[coveralls]

Coverage remained the same at 81.53% when pulling ddd2625 on xlshen:master into f8b12cd on weui:master.

[yeeez]

我觉得应该是先判断是否有传入props.component，如果没有，用FlexItem.defaultProps中的值，也就是div来作为component，如果有传入，则直接使用参数，比如span来作为compoent。难道直接使用Componet就可以达到这个效果？

[xlshen]

@yeeez 根本原因在react编译时把component当作普通标签处理了，而不是变量处理：

<component className="weui-flex__item" {...others}>
  { children }
</component>

处理结果：

var FlexItem = function FlexItem(props) {
    var component = props.component,
        children = props.children,
        others = objectWithoutProperties(props, ['component', 'children']);

    return React__default.createElement(
        'component',  // 此处应该为component变量，而非字符串
        _extends({ className: 'weui-flex__item' }, others),
        children
    );
};

so...悲剧出现了

可以通过pull requests文件中修改办法解决该问题

[yeeez]

@xlshen tks，感觉项目停了，请求都没有受理

[tsheng]

Looks goods. Please go ahead to approve this PR. Thanks.

[z2014]

#310