warn computed properties that clash with existing properties (close #4562)
warn computed properties that clash with existing properties (close #4562)

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