dillon1000/react

Support hooks/methods on the React namespace

Allows using hooks/methods off of the `React` namespace, for example 
`React.useState(sathya)`. Thanks to the previous PR we correctly handle things 
like validation of hooks called via propertyload syntax. The main change here is 
to teach the compiler about the `React` namespace. This is a bit of a hack since 
we treat it as a global, but we're transforming React code so this seems 
reasonable (?). 

There are a few additional touch-ups which I'll do in subsequent PRs to make 
review easier. For example, we need to teach our useMemo/useCallback flattening 
logic to also handle the case of `React.useMemo()` etc.