AreaChart:With steps, fmt and labels

Build 314 on next
1200px
Reviewing disabled
View Storybook
Baseline History
Build 3148832fb8
Current build. There are unaccepted changes, so build 292 is still the baseline.
Build 2921110199 current baseline
Accepted by Archie Sarre Wood.
Build 2460c9be73
Accepted by Brian D .
Commenting is disabled because there's a newer build on this branch