Enforces corejs v2 for babel
Enforces corejs v2 for babel

Corejs 3 got released which adds noisy warning messages. Force storybook
to use corejs 2 instead until proper v3 migration which is breaking change.
storybooks/storybook,storybooks/storybook,storybooks/storybook,storybooks/storybook,kadirahq/react-storybook,kadirahq/react-storybook,storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,storybooks/storybook,storybooks/react-storybook,storybooks/react-storybook,storybooks/storybook