[Bug Report] Tabs , carousel should use the variable for the name to calc their children

### Element UI version
2.13.0

### OS/Browsers version
mac os

### Vue version
2.6.0

### Reproduction Link
https://github.com/ElemeFE/element/blob/dev/packages/

### Steps to reproduce
1)
https://github.com/ElemeFE/element/blob/dev/packages/tabs/src/tabs.vue
line 61 vnode.componentOptions && vnode.componentOptions.Ctor.options.name === 'ElTabPane');
2) https://github.com/ElemeFE/element/blob/dev/packages/carousel/src/main.vue
line 205 this.items = this.$children.filter(child => child.$options.name === 'ElCarouselItem');

### What is Expected?
'ElTabPane' and 'ElCarouselItem' should be the default value ,but can be give the other value

### What is actually happening?
not the variable