chore(parser.spec): fix an IE conditional test with a typo (#5102)
chore(parser.spec): fix an IE conditional test with a typo (#5102)

* chore(parser.spec): fix an IE conditional test with a typo

* check children.length is 0, instead of undefined

KingMario/vue,xueyaodeai/vue,lizhiyao/vue,cnchanning/vue,cnchanning/vue,Kingwl/vue,Kingwl/vue,vuejs/vue,Hanks10100/vue,Jinjiang/vue,xueyaodeai/vue,KingMario/vue,lizhiyao/vue,Jinjiang/vue,Jinjiang/vue,Kingwl/vue,Kingwl/vue,xueyaodeai/vue,Hanks10100/vue,Hanks10100/vue,lizhiyao/vue,lizhiyao/vue,vuejs/vue,KingMario/vue,Ddder-FE/vue,optimizely/vue,Ddder-FE/vue,Ddder-FE/vue,xueyaodeai/vue,vuejs/vue,cnchanning/vue,Jinjiang/vue,vuejs/vue,Ddder-FE/vue,Hanks10100/vue,KingMario/vue