Update react in / from 16.4.0 to 16.6.1

[dependencies]

Dependencies.io has updated react (a npm dependency in /) from "16.4.0" to "16.6.1".

16.6.1

React DOM

• Fallback should not remount every time a promise resolves. (acdlite in #14083)
• Fix bug where Suspense keeps showing fallback even after everything finishes loading. (acdlite in #14083)
• Fix unresolved default props in lifecycle methods of a lazy component. (gaearon in #14112)
• Fix bug when recovering from an error thrown during complete phase. (gaearon in #14104)

Scheduler (Experimental)

• Switch from deadline object to shouldYield API. (acdlite in #14025)